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Claude Opus 5

1167 pointsposted 6 hours ago

631 Comments

postalcoder

6 hours ago

I think the most important thing here is not absolute performance. It's that organizations now have access to a Fable-ish model without Fable's 30-day data retention requirement[0].

> "Consistent with prior Opus models, Opus 5 does not have data retention requirements for general access."[1]

On the Opus model release page, the reason why Fable doesn't have an ARC-AGI score is because of that retention policy[2].

0: https://support.claude.com/en/articles/15425996-data-retenti...

1: https://www.anthropic.com/news/claude-opus-5

2: https://xcancel.com/arcprize/status/2064399134099153344

fny

3 minutes ago

Anthropic offered ZDR for Fable on AWS bedrock from the beginning.

cjonas

a few seconds ago

Really? I was unable to use it in our org without having to enable the provider_data_share setting... From the docs[0]:

> To use this model, you must opt in to provider data sharing by setting your data retention mode to provider_data_share via the Data Retention API

0: https://docs.aws.amazon.com/bedrock/latest/userguide/model-c...

alvis

6 hours ago

Also the cost per task. It appears to be significantly cheaper, cheaper than sonnet!

x313

5 hours ago

The numbers from Anthropic seem heavily cherry-picked, Artificial Analysis has Opus 5 at 1.25x the cost of Sonnet and 2x the cost of GPT 5.6 and K3.

https://artificialanalysis.ai/?cost=cost-per-task

I don't understand how the K3 numbers keep coming out cheap for people. I recently started to add it to my security auditing benchmarks and found it was going to cost about twice as much as Opus 4.8. It blew through the $100 budget I'd set at like 11%. In the tasks I'm doing it seems crazy expensive because it chews so much, burning a tremendous amount of tokens.

InsideOutSanta

3 hours ago

I think the way people usually compare pricing is fundamentally flawed. You can't compare token prices because different models use different tokenizers, and you can't compare tokenizer-normalized token prices because different models at different settings use more or fewer tokens to complete the same task at a different level of quality.

Based on my entirely subjective experience, the $100 Moonshot plan using only K3 is comparable to the $200 Anthropic deal using the whole Fable allocation and Opus 4.8 for the rest.

KronisLV

an hour ago

> Based on my entirely subjective experience, the $100 Moonshot plan using only K3 is comparable to the $200 Anthropic deal using the whole Fable allocation and Opus 4.8 for the rest.

For me, the Moonshot 100$ plan felt like it gives me lower total amount of work I can do than the Anthropic 100$ plan (probably within like 30% of each other). Kimi has way more generous 5 hour limits (never hit those once, whereas I do regularly with Opus) but the 7-day and monthly ones are lower. However, with the annual billing, Moonshot's 200$ tier plan becomes way better, because you get it for 159 USD per month.

There's also the odd thing of Anthropic's 100$ plan charging me 108 EUR so seems like their sticker price does not include VAT but Kimi's did, cause I paid like 87 EUR. Wrote down some initial thoughts at https://blog.kronis.dev/blog/kimi-k3-is-out-is-anthropic-don... but it's hard to do exact comparisons (even the same task will have way different real token amounts per model).

Still, Kimi K3 is a pretty cool model! On high reasoning, it was pretty close to Opus 4.8 and didn't seem to waste as many tokens as Max.

SwellJoe

3 hours ago

I got the $19 plan, and it's anemic. One tiny task blew through the 5-hour budget and 19% of the weekly budget. A completely useless amount of usage. OpenAI's $20 plan feels like 100x more generous (I don't think I'm exaggerating here). Someone in another thread said their plans are cheaper in China, maybe that's the difference, I dunno.

But, I'm finding Kimi K3 terrifyingly expensive in the way that Fable and GPT 5.5 Pro are at token rates. Not as expensive as those, but expensive enough to where if you don't put a budget cap on it, you might wake up bankrupt if you leave a task running overnight. Not because of the per-token cost, but because how many tokens it's going to burn.

nullify88

2 hours ago

In the $19 plan, I've been able to reverse engineer both an android APK and firmware (in Ghidra and Radre) for a baby rocker and build a quick PoC application in my session limit. And then further refined the app in another session at another point in time without leaving Opus. I dont consider that to be a tiny task. How are you blowing through your usage?

SwellJoe

2 hours ago

I have no idea. Seems like normal stuff. I used Kimi Code with K3 to add support for Kimi Code to flar (https://swelljoe.com/post/i-let-every-agent-implement-its-ow...), a task I've done with almost every major model/agent combo. Most show up as a blip on the usage chart...it's basically usually one file, a README update, and adding the agent name to the CLI.

Then, I added it to my benchmark of security vulnerability auditing capability, and it burned a bazillion tokens, burned through the 5-hour limit, burned through $100 in extra usage I'd allocated, and was only 11% finished. That's more expensive than any model I've tested other than GPT 5.5 Pro on this task.

These are things I've done with a bunch of other models, I feel like I have a notion of what they ought to cost, and with K3, they end up being crazy expensive. (And it seems to be a function of how many tokens it burns accomplishing the tasks.)

try-working

3 hours ago

I have the second largest Kimi plan, the Chinese version. When K2.6 was their latest model, the quota was good; it was like GPT $100 is now or what the $20 version was in December.

When K2.7 was released, they cut quota by 80%. I can't tell how much they have further cut it after the K3 release because it's barely worth using at all. I just use it in my model router since I have the annual plan paid for.

It's just not a serious model or company.

InsideOutSanta

2 hours ago

Yes, the OpenAI plans are much more generous than both Moonshot's and Anthropic's. It's the only provider of the three where the $20 plan is at all usable for programming.

bg24

https://www.vals.ai/benchmarks/vals_index

!!! Vals !!!

Vals Index Opus 4.8 > 5.0 goes from $2.90 to $8.54, for 4% gain ... That is a massive cost increase. Sure, 20% cheaper then Fable, but that is a 3x price increase compared to Opus 4.8 in that test.

https://artificialanalysis.ai/models/claude-opus-5 https://artificialanalysis.ai/models/claude-opus-5#price-cos...

!!! artificial analysis !!

Cost per task is second highest, right below Fable.

* Fable: $2.75

* Opus 5.0: $2.03

* Opus 4.8: $1.80

* GPT 5.6 Sol: $1.04

* Kimi K3: $0.95

Looks like interest levels of cherry picked cost in their report. Cheaper model, clearly NOT. More expensive in both benchmarks.

spider-mario

an hour ago

Your numbers are for “max”. Opus 5.0 “max” is $2.03. Opus 5.0 “high” (competitive with Claude 4.8 “max” on that index) is $1.06, less than the $1.80 you are quoting for 4.8 max.

That the most expensive variant is expensive doesn’t really tell us much.

benjiro29

an hour ago

Same answer i gave to somebody else up here...

If you start to drop effort levels, you need to compare to the competition models. So GPT models on the same ~intelligence level, are then 50% cheaper.

You see the issue? Its still a expensive model, and from my understanding, it still uses the old tokenizer.

Going to be interesting to see when GPT 6 comes out (very soon).

manojlds

3 hours ago

Opus 4.8 was already shown to be cheaper than Sonnet 5 when Sonnet 5 was released (by Anthropic)

artursapek

2 hours ago

It's definitely not cheaper than Sonnet on my benchmark, but it's cheaper than Fable and outperforms it. Which is big IMO. https://revise.io/errata-bench

abixb

5 hours ago

So the rumors were right, Opus 5 was indeed being polished up for release. Huge improvements in GDPval-AA v2 too -- great for some of the knowledge work-based agentic workloads I run.

Also glad they still kepy Fable 5 on "credits only" access. I think we're going to start seeing model providers gate top-of-the-line models behind pay-as-you-go API rates/credits while subsidizing other models on monthly subscriptions.

jpk2f2

5 hours ago

It's still available on at least some subs, they emailed me recently notifying me that I still have access.

saratogacx

4 hours ago

2 hours ago

That tweet says:

> Opus 5 can silently fallback to Opus 4.8 (without any notice) on the serverside if you hit a guardrail

But https://support.claude.com/en/articles/16049681-why-claude-s... says (emphasis mine):

> These checks cause Claude to _visibly_ fallback from Opus 5 to Opus 4.8 [...] You'll see a notice explaining that the model switched, and the response will be labeled with the model that answered.

So who is right? I know for Fable I am visibly told, is this tweet trying to say it is silent against what Anthropic is saying?

SwellJoe

an hour ago

So, announcing the fallback is better than doing it silently, but the fact that Fable falls back frequently for the kind of work I do (a lot of security oriented stuff lately, but it falls back on seemingly random stuff, sometimes, too), means I reach for it less. Getting interrupted mid-task makes it much less valuable. If I have any suspicion I'm going to hit the guardrails, I'll use something else.

solenoid0937

2 hours ago

Is some random guy on Twitter right, or official support docs that explicitly describe this scenario?

lossolo

18 minutes ago

It's showing you're switched to 4.8, i just hit that while doing security research.

gonzalohm

5 hours ago

I don't understand how the data retention works. My company has an enterprise license with no data retention but if I ask Claude about past conversations, it remembers. So surely the information is being stored somewhere

NiloCK

4 hours ago

Opus 4.7+ and Fable are both much more aggressive than prior models with respect to writing memories to a location that's effectively quasi-private for them. It's device-local (so passes retention constraint), and you can see it, but only if you go looking for it.

It's a funny design/affordance. I do see them often writing memories of things that that feel unlikely to be important going foward / with other tasks, but I don't see them clearly getting tripped up by them as prior models used to. (eg: Since you're running Ubuntu in Canada, here are some drills you can try to help your kid hit a baseball more consistently.)

persedes

5 hours ago

You most likely are referring to the local jsonl files where claude has your sessions etc stored.

mh-

5 hours ago

It could just be the memory features.

In my enterprise-seated account I see slightly different options available (vs. my personal account) in the Capabilities section:

  Search and reference chats
  Allow Claude to search for relevant details in past chats.

  Generate memory from chat history (Legacy)
  Allow Claude to remember relevant context from your chats. Memory includes your entire chat history with Claude.

Claude Code? It stores a memory.md file.

arrowleaf

6 hours ago

> Updated over 2 weeks ago

I hope we get clarification on this, I can't find anything claiming that it is compatible with ZDR.

collinrapp

5 hours ago

Maybe I’m misunderstanding you, but if you scroll to the bottom of their [1] link to the Opus 5 announcement, under “Getting started,” it explicitly says:

> Consistent with prior Opus models, Opus 5 does not have data retention requirements for general access.

solenoid0937

5 hours ago

It's in the article.

doctorpangloss

5 hours ago

do you mean, that organizations now have access to Fable-ish pelican drawing?

gigatexal

5 hours ago

insane pricing:

" Claude Opus 5 is available today on all platforms, priced at $5 per million input tokens and $25 per million output tokens (the same as Opus 4.8)"

RazorBucksICO

3 hours ago

I think for the value of the outputs that’s still a good deal. Keeping the same price as the prior model makes sense to me. That is if the model size is about the same in the cost to serve has not substantially changed. Now I would have expected efficiency gains for inference, but there is no way to know as a customer.

At the end of the day, they have established a strong brand and if they can get away with a 95%+ gross margin on inference entirely from the status premium, then I suppose that’s good for them. Apple does the same thing, and I don’t fault them for it.

oblio

3 hours ago

Why is it insane if it's the same as the previous version?

gigatexal

2 hours ago

"insane" that they kept the price the same and didn't jack it up, my bad for the ambiguity.

jjcm

4 hours ago

Doing testing with it now, specifically for image->html conversion.

Previously Fable was the best at this, followed by Gemini 3.1 pro (a surprising #2, but Google has great vision models).

Opus' results seem to be more accurate than Fable, following the design source of truth better.

Example results:

Design source of truth: https://image.non.io/73e239a3-880f-4793-b65f-4810be2d9378.we...

Opus 5 build: https://html.non.io/solaraOpus/

Fable 5 build: https://html.non.io/solara/

Note the buttons - for fable they're pill buttons, opus got the rounded rectangle nature of them. Opus' images are closer to the source of truth as well (both LLMs were provided with image gen capabilities for the assets).

Running more tests now, but preliminary results are saying this is indeed better than Fable in some areas. Crazy.

jjcm

4 hours ago

Here's another test of a cyberpunk ramen shop website.

One thing I've found LLMs have a lot of difficulty with is angular cuts / elements that aren't easily representable with CSS. Cyberpunk aesthetics are generally a great test of that, since they have a lot of microglyphs / window decoration.

Design source of truth: https://image.non.io/9d5fed20-b476-49d3-841b-37eb553fb88e.we...

Opus 5 build: https://html.non.io/neonRamen/

Thoughts: It does a really, REALLY good job at these angular cuts / microglyphs. The responsiveness is off, but I'm very impressed at how well it did here. One way I think of it is "how close to a finished product did this get me?". Opus gets you like 90% there.

winwang

3 hours ago

Several other commenters have disparaging the design seemingly mostly due to its AI-generated nature, or maybe they actually do dislike cyberpunk.

Personally, I think being able to have these design languages be easily prototypable is fucking awesome. Great tests! (But a tad low-performance/janky, somehow). Though, I also like the cyberpunk aesthetic. Very on-brand(?) that AI generates it, hah.

echelon

4 hours ago

God damn, we are living in the future.

I love this so much.

Designs like this would never have seen the light of day in the cellphone incrementalism / corporate memphis era of tech. Now people can be weird and awesome again.

This is 1980's cyberpunk / late-90's Matrix / early-00's sci-fi UI. Great ideas that died to frutiger aero (which isn't a bad design aesthetic) and flat design (which is).

This is fun and it's got great colors and I love it.

It's so refreshing to see this.

AI rules. This is the best timeline.

andersonpico

2 hours ago

What do you mean designs like this? This is 2016-cyberpunk-neon-era inspired by video game interfaces, these are not uncommon at all. Google something like "discord cyberpunk theme" or "cyberpunk rice site:reddit.com/r/unixporn" and you'll find endless examples. This isn't suprising at all obviously.

brailsafe

18 minutes ago

I'd say the only thing it's a newish aesthetic for is web UI that isn't implemented in Flash, but even then there's been periodic resurgences. Command and Conquer, Starcraft 2, I'm sure there are tons of examples I'm unaware of.

The only recent novel addition—I'd speculate—is the specific influence of Cyberpunk the game with its shiny surfaces and pink highlights, but even then it's hardly new.

GPerson

2 hours ago

I feel that AI has deeply diminished my ability to be weird and awesome, because my weird and awesome takes time and the results I can share with others are outshined by the machine.

jjcm

2 hours ago

IMO what makes things awesome is human hours invested.

The ramen shop website above is pretty, but it's a veneer. It's not weird and awesome, it's just a representation of a site. I spent about... 7 minutes of my life making it. It's a tech demo, nothing more.

If someone actually poured their heart and soul into a vision for a cyberpunk themed ramen cart, and happened to use this because they didn't have the capabilities or funds to do a proper design, suddenly it becomes less of a veneer, and more just a component in the wider vision of that individual. Their human hours poured into the wider thing that's the business becomes what matters.

Ideally what AI does is it amplifies the hours we do pour into things that are weird and awesome, it doesn't replace them.

ultimafan

an hour ago

Strongly agree, I feel like my passion for development as a whole has waned away as AI has gotten more prevalent.

We do things to achieve some end result but it's the journey there that is the most cathartic to me. The "skilled crafts" element of development where careful deliberation and hours of tinkering to get any kind of appreciable output you can admire has been replaced with a one stop dopamine button that skips the whole process that I could find myself getting lost in.

I've taken up carpentry/metal working as a result. Maybe someday we'll have live in robots that do the same for those hobbies that AI did for programmers but I can't see it happening any time soon.

hangrybear666

an hour ago

Yeah I feel the same. That's why I've canceled my claude subscription and code everything by hand again, because building skill and mastery in a craft is fun and rewarding. Having a machine do it for me is neither. Fortunately coding is my hobby so there is zero pressure to optimize it.

At my workplace management is pushing AI, so I am using it in order to establish sensible and thoughtful applications of it and in order to know when to call out colleagues for pushing mindless automation out of complacency or blind obedience.

jjcm

4 hours ago

Designs are here if you want to play with em: https://diffui.ai/app/canvas/68c5bb3d-467e-4841-b49d-c008e72...

This was just from a prompt "A cyberpunk themed ramen food cart website. Should feature menu, locations, and an ability to put in an order for pickup. Simple and clean website with angular cyberpunk microglyphs, pink/teal colors."

wilkystyle

2 hours ago

This comment resonated with me so much, and it seems to be a minority view (at least on this website).

I have found myself empowered by AI to tackle all sorts of things that would have too high of a barrier to entry for me to want to spend my limited time on as a busy father who is also working at a small startup.

And when I say that, I do NOT mean that I can crank out a bunch of slop and label it as something I produced even though I don't understand the code. I mean that I can do things like go back to college math that I never appreciated at the time and honestly felt too scared of. I mean having an on-demand math tutor that ask clarifying questions to as I struggle through the problem sets.

I have found that it actually accelerates learning how to code in various problem domains because I can tell it to answer my questions at a conceptual level and be a sounding board, but to never actually write code for me. It can review the code I write and gently nudge me without giving away the answers, so that I still struggle through the learning process and actually gain the knowledge.

And finally, for the first time in like 10 years of feeling overwhelmed and daunted by the prospect of learning game development (I have no background in that), I have found Codex to be an incredible boon for learning with the Godot engine. It helps me understand the terminology so that I know what to search for and what documentation to read. It helps me map my computer science knowledge from other domains into the game world, and to understand why things are structured the way they are. And because Godot saves all of the scenes and geometry and lighting and shaders to the file system as text files, Codex can inspect the results of the work I'm doing in the IDE and help me track down things I'm stuck on, and explain what the issue is. For example, why my pre-baked global illumination lightmap is breaking my ambient lighting configuration.

I know it has never been easier to cheat and skip the hard work that results in actually learning something, but for me, personally, I cannot believe the incredible value that $20 a month has provided me. I have never been more excited and eager to dive into tackling hard things I had previously been afraid of or simply too overwhelmed to attempt.

It has never been easier to quickly prototype and get a feel for some idea you have in your head to see if it even has legs. Simply seeing a quick prototype of an idea is often all of the excitement and fuel I need to then take it and make it a real project.

hangrybear666

37 minutes ago

Your approach seems sensible. Especially the part about discussing concepts to gain understanding instead of having output generated for you to avoid having to think. Unfortunately, most people are interested in shortcuts and thinking less and will ultimately deteriorate in their abilities the more they abuse these tools to skip the learning process.

aaa_aaa

3 hours ago

No we are not living in future. Design is ugly, and immediate put off because it smells AI.

djeastm

9 minutes ago

We could say the same for the first factory-made clothes. Not as nice as the hand-tailored ones, looking a bit "off" when people wear them compared to custom-made, but orders of magnitude cheaper and more convenient.

FranzFerdiNaN

3 hours ago

Reading your comment I had to think of that tweet about someone taking a part of a Monet painting and claimed it was AI generated, and people immediately started calling it horrible and soulless and smelling like AI.

bonoboTP

2 hours ago

Obviously. Artistic value is not in the object, but in the relationships to other humans. The point is not Monet but the people you discuss Monet with. Monet is a tribal rallying point you can synchronize around. AI is not as good for this, because it's cheap. It's not scarce enough. And doesn't offer a human story you can bond around.

aaa_aaa

3 hours ago

Well this is no Monet for sure.

newsy-combi

2 hours ago

Humans are capable of producing slop too. Maybe the cutout does look like AI. Given Monet's blurry style and repetitive content (he made 250 water lily paintings), this is not surprising. When you strip the cutout of its context, it can look more like AI too because the lighting and composition will look arbitraty compared to the whole picture.

Btw, if websites would only include the frontend dev's own hand painted images, we would also revolt at the sight of human slop. It's not just AI.

The whole point is that good artists are capable of producing non-slop, and to this day they're the only group of which this is reliably true.

tackta

41 minutes ago

It is because it is an image on a screen.

Water Lilies are enormous paintings. They are breathtaking in person because of their scale. Monet wouldn't be Monet if he had only produced images on a screen.

Art is good or it is shit, based on personal taste. Just like food, no one can tell me what food tastes good or tastes bad.

AI Art seems to produce strong emotions in people who don't go to art galleries. I love modern art, I am a huge art snob but if you want to see slop, go to any modern art gallery. Personally, I would say for my taste, at least 70% of all art at any gallery is basically shit.

Like food also, the presentation matters. To believe there is no possible way to print out a 6 foot tall by 10 foot long AI generated image that would look awesome hanging in a gallery is stupid.

HaZeust

2 hours ago

Then tell it that, and it'll give you the output you desire.

theappsecguy

4 hours ago

We are going through yet another generational wealth transfer and people are being squeezed to the absolute brim with layoffs and daunting lack of career prospects.

But sure, lets cheer that funky website designs are back on the menu…

Mtinie

3 hours ago

Assuming no change from the baseline, I’d rather have one positive thing versus nothing positive.

signatoremo

2 hours ago

Why don’t you start a movement to fight for equality, and I’ll join you? Why are you still here and not taking actions?

In the mean time, I’ll unashamedly continue to cheer for creativity and innovation. Note: I don’t even like this website design.

kypro

3 hours ago

I'll add to this...

The "funky" websites of the past were mostly a result of tech immaturity and a lack of profit motive.

Businesses have been able to easily install templates like this for at least a decade. They don't because stuff like this looks cool but isn't very functional.

AI isn't going to make your local restaurant have a funky website, it's just going to make everyone who use to work directly and indirectly for that company unemployable. And even the local restaurant will close down because they can't compete with the multi-national competitor that has automated their kitchen with AI.

andersonpico

2 hours ago

I agree with most of your comment with one exception: It will never be economically viable to replace kitchen staff with AI.

kypro

26 minutes ago

> It will never be economically viable to replace kitchen staff with AI

Can you expand? Specifically what is it about humans that AI and robotics could not replace?

mainmailman

2 hours ago

Unrelated question, what’s your favorite flavor of Kool Aid?

ai_fry_ur_brain

4 hours ago

Because they're incredibly ugly

echelon

4 hours ago

It's gorgeous and the world doesn't have enough of it.

wilkystyle

2 hours ago

I was gonna say, you can dislike it because of the design, but understand that that's a subjective opinion that has nothing to do with whether AI is awesome. I actually like these designs, personally.

abidlabs

17 minutes ago

I was curious to see how open weight models would do on this task so I passed in a screenshot of your source of truth and here's what 2 of the best code-generation models that allow image inputs do:

Inkling (not too great): https://cdn-uploads.huggingface.co/production/uploads/608b8b...

Kimi 2.7 (really well, esp. note that this is the predecessor model, not the latest Kimi3): https://cdn-uploads.huggingface.co/production/uploads/608b8b...

Here's how I tested them: https://huggingface.co/spaces/abidlabs/vlm-screenshot-to-web...

https://huggingface.co/spaces/abidlabs/vlm-screenshot-to-web...

chriscamargo

4 hours ago

This is an awesome test! Thanks for sharing the results. Opus 5 is very impressive.

Out of curiosity, what app is that Design source of truth screenshot from?

jjcm

4 hours ago

That's from my own tool. I left figma to build a diffusion-based UI tool. Here's a show hn post with some more info: https://news.ycombinator.com/item?id=48995754

Edit: Generation was down, back up now. Apparently just hit my $1000 cap for the openai api. Upped it to 10k. Growth!

IanCal

11 minutes ago

Huge fan of the non-seat/monthly based pricing. Do you need it to be higher to not just cover costs but also make a profit?

afro88

3 hours ago

IMO a much better test would be designs that aren't AI to begin with. Much more useful to see how well a model can html an image design without slopping it up

bottlepalm

4 hours ago

I just clicked your links and then read your comment after - my first impression was the Fable version looks way nicer.

jjcm

4 hours ago

I agree the fable version looks nice - the rounded hero image for instance.

Opus though followed the source of truth better imo. The details are more present.

Fable filled in the gaps for things it wasn't able to do (ie in the design the hero image goes behind the nav), which resulted in a better looking page that was more divergent.

kccqzy

3 hours ago

Same. I like the Fable version better. Better colors, better choice of font sizes, better column sizing. Also small things like the “Experience” section header being orange rather than gray, which Fable got right and Opus got wrong.

It seemed to me that Fable meaningfully improved on the original design more than just faithfully executing the original design.

andersonpico

2 hours ago

I liked the Opus version better if only because the responsiveness is less broken.

erikw

4 hours ago

Very interesting that Fable took more creative liberties. Have you tried giving Fable the same task, but also specifying that it implement a pixel-perfect design? I think that I prefer the Fable implementation. I find the UI elements in the Fable implementation to have more contrast, which feels more usable to me. I also like how the right padding on the "Book Your Escape" CTA in the upper right matches the top and bottom padding, which I think is an improvement over the mockup.

jjcm

4 hours ago

All of these are using a build skill which specifies rules for building it, requirements to create a pixel perfect implementation, and tooling to help in that process. Here's the build skill / instructions I pasted in to both of them:

> Create a web page implementation from the following instructions:

> https://diffui.ai/build/Spa_Booking_Experience_build.md?auth...

hbcondo714

2 hours ago

> You are an elite frontend engineer and design-to-code specialist. The design image is the primary source of truth; your code is the translation layer. Do not reinterpret or "improve" the design into something generic — reproduce it faithfully.

Thank you for sharing this. I was just using OpenAI's Product Design plugin[1] to create designs but it just didn't reproduce it in code faithfully so will need to try this.

[1] https://openai.com/business/plugins/product-design/

jjcm

2 hours ago

http://impeccable.style/ also just released their latest version which has some image->html conversion. They just released a couple days ago and haven't had a chance to try, but I suspect theirs is a bit more robust than mine for pure LLM instructions. Worth trying and comparing it with mine.

Xenograph

4 hours ago

Is this with browser tooling attached to the agent for review/iteration?

jjcm

4 hours ago

yea this was just straight into claude desktop / its standard tool usage, on "high" thinking. The ramen website is on "extra" thinking.

paxys

6 hours ago

Looking at all these releases it’s not a surprise that model routing is the fastest growing segment in AI right now.

There are 10+ LLM companies, each with dozens of models of different modalities, each model with multiple size variants, then different “thinking” levels, then agentic modes, “pro” modes, a “fast” option, standard vs flex vs batch execution. And of course each end combination has a different input/output/cache token price.

Companies that say “give me a prompt and I’ll route it to the most ideal and cost effective model and setting for you” are capturing a ton of value from a gap that model developers don’t seem to understand exists.

ai-x

5 hours ago

siva7

4 hours ago

Why should it? An Anthropic model is architecturally optimized for Anthropic models, routing it to Kimi makes zero sense

anon7000

4 hours ago

Which is why 3rd party routers which do route between different models may have an edge. It means they can compete on cost, and it’s definitely not clear that the architectural optimization is always going to be higher quality or cheaper. It might be, but everything changes constantly, so locking into a single model family/company is very much not ideal

vanuatu

4 hours ago

i think you're thinking of subagent routing

model routing in this case is cross-provider

Imo the main issue behind model routing is you need to figure out how much intelligence a new task takes, which is a very non trivial problem. Presumably, a organization knows this about their own tasks and is better suited to built in-house compared to outsourcing to a vendor.

CuriouslyC

4 hours ago

Model routing by the model itself requires the model to pull in a lot of context and it's likely more efficiently just done by people with the context already in their head, even assuming the model is perfect at routing (which last I checked, Claude definitely isn't). I wouldn't trust ML model routers.

hnfong

6 hours ago

Because they're trying very hard not to understand it.

Otherwise the expensive-yet-powerful model probably won't see much revenue. How much money is there in bleeding edge scientific research? There's a lot, but there's even more existing capital in paying people people to do college level paperwork, and the bulk of those traffic gets routed to the cheapest model.

You mostly don't need super powerful AGI to replace the paper pushers, but the frontier labs are trying to position themselves as being uniquely capable of producing super powerful AGI, and also be the ones replacing office workers.

Not sure how it will work out for them, but I think model routing is going to poke holes in that narrative. That's why I think they're trying very hard not to understand model routing exists.

ip26

2 hours ago

It wasn’t long ago at all that the chief problem was “can AI even help me with this” (cost be damned). Until a time when the answer is an unmitigated “yes, obviously”, the frontier labs have everything to lose and nothing to gain on routing, because if they screw it up you might incorrectly decide “nope, it can’t help yet” due to a poor routing decision.

TeMPOraL

5 hours ago

Who are the customers though? Honest question, I'd like to understand it.

For me, anything other than current best available SOTA for any task is unacceptable. The only routing rule I need is "the most powerful model I still have flat-priced quota available for". I mean, why settle for less?

btown

4 hours ago

There are two types of users: those who are able to use subsidized rates, and those who need to use API rates due to audit requirements, enterprise billing, etc.

Model routing for subsidized users takes the form of a "use Opus 5 subagents for implementation" type of system prompt. You lean into a single provider, build tooling around that, and your savings are far beyond anything multi-provider routing can get you.

Model routing for enterprises is far more complex - approaches like https://fireworks.ai/blog/kimik3-fable become necessary for cost control.

pzo

4 hours ago

on top of that there is also additional factor: speed - sometimes if task is easy you do care to finish it faster.

There is also matter about convenience - when I ask some small easy question often I don't bother to switch the model or forget in prompt to ask faster/cheaper subagent.

kxxx

5 hours ago

It's very common to use a lesser model for a lesser task, resulting in same quality output. End result: save money while being faster. In many cases, it's a pure win-win.

lostmsu

5 hours ago

But in other many cases you have to redo the work directly or indirectly, and you are more expensive (for now) than even the most expensive models, so sounds like a total lose.

paxys

4 hours ago

I’m assuming you don’t pay per API call. Every mid-large sized business in the world does.

Slartie

5 hours ago

And you do not have flat priced quota for Fable 5, right? Because nobody has, as far as I know. So you'll probably not route any task to the "current best available SOTA".

Also: quota. Implies you do not have unlimited access even for flat prices. Which in turn implies that as soon as you hit the quota on the most expensive flat price plan, even you will suddenly discover the magic of economically sensible behavior.

abi

4 hours ago

Fable 5 is included in the Claude Max subscription. I've gotten close to the limits this week and last but haven't hit it yet.

dgellow

4 hours ago

But Fable is only available for 50% of your Max quota as far as I understand

msabalau

5 hours ago

Not everyone is you. Other people probably have a range of tasks that can accomplished with different models.

Certainly if I'm confident that I'm going to get what I need from a faster model, that's what I want to use, rather than wasting time grinding away for the sake of saying of the same answer came from a SOTA model.

Given that every chatbot does offer a range of models, it seems clear people do choose among options.

internet2000

4 hours ago

toss1

5 hours ago

I'm not a customer of those routing systems, but I quite often use different Claude models for different tasks. While most tasks were Opus 4.8, I often used 4.8 to make a plan, prompts, and package kit to setup Fable for a bigger project, then run it on Fable. Or, for broad single-task searches Sonnet with or without "Research []" turned on seemed to work best both faster, lower overhead, and less verbose answers (when I didn't want it).

OFC, YMMV

awongh

5 hours ago

what's the threshold for model routing where you're willing to trust the router?

For coding my own work I don't trust the model router, and it would have to be shown to be to save a real dollar amount.

From a buying perspective it's a hard sell to save x but lose out on bugs you are probably introducing at an unquantifiable severity and frequency. How much is it worth to hedge your bets by doing every single inference request on the frontier model?

How much will it cost to go back later and fix things, but also the meta question of how to be able to decide on a hypothetical unknowable? (You'll never know how much better or worse your code was gonna be, it's untestable at a project level)

binary132

4 hours ago

you trust the service provider but not the router?

weird, but ok

awongh

4 hours ago

I don't want to save money so badly that I'd possibly undercut the quality of the code that gets created.

*edit to add: that code quality (or lack of quality) is it's own cost

owenthejumper

3 hours ago

I am not convinced this will end up being a domain of the ‘routers’ vs the clients, as in harnesses themselves. Thoughts?

ModernMech

3 hours ago

lol I had to get ChatGpt to explain to me the difference between 5.6 sol, 5.6 Terra, 5.6 Luna, 5.5, 5.4 mini, 5.3 spark, and then there is low, medium, high, extra high, max, ultra, and pro… I still don’t really know, it feels like ordering hot wings.

simianwords

5 hours ago

Openrouter should ideally kill in this space and make their model agnostic infra like memory, harnesses, chat applications.

verdverm

5 hours ago

binsquare

5 hours ago

given that i couldn't even use fable without it downgrading to Opus, this is just a straight upgrade for me

Freedumbs

3 hours ago

Opus 5 also downgrades. it's now Fable -> Opus 5 ; Opus 5 -> Opus 4.8. Unclear why they want to nerf their own products with sometimes right classifiers. I guess the government ban might've been real and not coordinated marketing?

ceejayoz

6 hours ago

Best can describe multiple things.

Almost as good for half the cost is something I'm very comfortable describing that way.

lelanthran

4 hours ago

> Almost as good for half the cost is something I'm very comfortable describing that way.

It's also not unusual in this context - many people describe the Chinese models as "best", because it's 80% as good for 20% of the price (or similar).

moffkalast

3 hours ago

Hopefully it's not like old Opus, where it was actually more expensive than Fable cause it thought for half an hour, got it wrong, and then thought until you ran out of credits trying to come up with a correction, while Fable just went for it and did it in one go, getting it right the first time without thinking more than a few seconds.

Got an endless list of stuff done with Fable, Opus 4.8 was like a flailing braindead idiot in comparison. Maybe this one is a bit better if it's distilled.

ProofHouse

6 hours ago

Best marketing

tshaddox

6 hours ago

The blog posts figure cites Frontier-Bench for its agentic coding score, and shows Opus 5 beating Fable 5 43.3% to 33.7%.

ActivePattern

6 hours ago

I think you're being overly cynical here. First, I don't see any claim that is the world's best model for agentic coding. Second, it is absolutely the best model in terms of coding performance vs. dollar, and it's raw performance seems very close to the frontier.

adam_arthur

6 hours ago

shwaj

5 hours ago

It would still be the best model per dollar if the score was 2% lower instead of 0.1% lower. Would it be ok to still give it the highlight color then?

How big of a lie is too big? Especially when no lie needed to be told at all: many including myself would have noticed the tiny 0.1% deficit and been suitably impressed by the Opus 5 result.

I think this is a case where you don’t understand the use case, not that the marketing department is making mistakes.

airstrike

6 hours ago

They cost the same if you're already at $200/mo

Aurornis

5 hours ago

Fable consumes your usage at a higher rate.

If you bought the $200/mo plan and you don’t use it much, using Fable for everything is fine.

maineldc

5 hours ago

I am not a tokenmaxxer per se but I blow through my weekly quota on my max plan in 3-4 days… fable would make that worse.

akmarinov

5 hours ago

Eh, not really. Fable does a lot better on coding than Opus 4.8.

Just this past week Fable was able to figure out a couple of small issues for me where Opus was failing to.

Also both are still somewhat bad at UI implementation. Opus more so

unclebucknasty

5 hours ago

Recent releases have said something to the effect (paraphrasing here):

"Use <less expensive or older model> for everyday tasks and <other non-critical stuff>. Use <more expensive or recent model> for complex coding tasks, refactoring large code bases, etc.".

Then, the next model/release emerges and the previous "best for complex" gets demoted to "everyday".

Obviously, it's all relative. But, it does beg the question: was the previous model really good for complex coding tasks or no? I mean, how is it now suddenly only good for the "easy" stuff?

hvb2

5 hours ago

> I mean, how is it now suddenly only good for the "easy" stuff?

Because your expectations have changed.

unclebucknasty

2 hours ago

I'm sure the marketeers would love for the public's assessment of complex versus easy to conveniently shift per their release cycles; or for the public to simply forget their prior marketing.

entropicdrifter

6 hours ago

I mean that certainly makes it best-in-class

siwakotisaurav

6 hours ago

Thanks for that, looks really good. I can see why they were constantly pushing back fable going out of the max sub with these benchmarks

kossae

6 hours ago

I wonder why FrontierCodev1.1's data lists Opus 5 as better than Fable 5.

lattalayta

4 hours ago

this feels like the perfect example of an LLM producing a long text document. And end users just using an LLM to summarize it without actually reading it

deweywsu

2 minutes ago

I wish I could just go back to the days before AI and cell phones. The world seemed to move fast then, but it really hadn't yet.

deet

3 hours ago

I compared the writing style of Opus 5 vs Fable 5, and Opus 5 continues many of the "Claude-isms" of its 4.8 predecessor in a way that Fable broke away from.

Opus 5 still uses "carry the argument", "worth stating plainly", ", and the trap", "The X matters more", the use of "move"

We need an "annoying English" benchmark.

- Fable 5 Max: https://gist.github.com/deet/3d97f854b48eac6658d642fa18bb24d...

- Opus 5 Max: https://gist.github.com/deet/1a43693a732dfccb4d0d914bfc42692...

Kwpolska

3 hours ago

Fable might be using those phrases less, but its writing is still terrible and exhausting to read.

arizen

2 hours ago

Could these complex/hard to read Fable outputs be sign of some kind of industrial level of intelligence, which us humans may have a hard to comprehend, while it may be also hard for machine to use simpler texts to properly outline all nuances and complexities of concepts it output?

solenoid0937

2 hours ago

Fable subagents communicate very effectively with one another, so this would be a reasonable take imo

dwaltrip

44 minutes ago

I've increasingly felt like Fable and I speak different dialects of English...

wfme

an hour ago

Agreed. I’ve interestingly found 5.6 sol to produce much better writing, and it can generally cut to the point much more effectively.

kranke155

38 minutes ago

Opus 4.6 remains unbeatable in my book. Fun to talk to. Fable felt very human. But not as fun.

markab21

26 minutes ago

Yes - THIS! I can't even believe how exhausting it is to read. I'm not sure why or what changed in Fable. Did they do this writing-style output to give it more token compression during/for training or to prefer output for less money?

I love it for a few things, but it's gotten really hard to spend any extended amount of time with it because of the lack of mental model I seem to be able to hold while working with complicated problems.

I'm guessing it's just not enough time doing RL on human feedback.

Check out the anouncement of Inkling (https://thinkingmachines.ai/news/introducing-inkling/)... the section in the middle

"Early in RL verbose, grammatical" (if you search) :

We need to understand the operator. The 5D line element is ds² = e^{2A(x)} (ds²_4d + dx²), where A(x) = sin(x) + 4 cos(x), x in [0, 2π]. The internal coordinate is periodic. The background is a warped product: metric g_{MN} where M,N = 0..4. The internal direction has metric e^{2A(x)} dx²? Wait, the ds² is e^{2A} (ds²_4d + dx²). So the internal metric is e^{2A(x)} dx². Actually if the total metric is ds² = e^{2A(x)} (ds²_4d + dx²), then yes, internal metric is e^{2A} dx².

vs. Post RL

We need determine eigenvalue problem for spin-2 fluctuations h_{μν}(x,y) with TT in 4d and depend on x. For metric of form ds² = e^{2A(x)} (g_{μν}(y) + h_{μν}(y,x)) dy^μ dy^ν + e^{2A(x)}? Wait internal metric is e^{2A} dx²? Actually ds² = e^{2A} [ds_4² + dx²]. So internal metric is e^{2A} dx²; warp factor same for 4d and internal? Yes. We need equation for h_{μν}(y,x) = h_{μν}(y) ψ(x) maybe with normalization. …

I can understand it with less cognitive load in the post-RL version versus early in RL. This resonated with my experience using Fable, especially digging hard problems; it feels like I'm reading the "early in RL" version of that model explanation.

kanodiaayush

an hour ago

I've found Opus 4.8 and Fable 5 both difficult to learn from purely because of how annoying their writing style is. I'm finding GPT 5.6 Sol to be much better for this.

DonsDiscountGas

2 hours ago

I think a signature Claude style of writing is good since it makes it that much harder to pass off Claude written text as human.

winwang

3 hours ago

I found 4.6 more amenable than 4.8 to style directions, we'll see how 5.0 does. Super-small-sample-size: I think part of its "Claude-ism" style comes from its propensity to try and "proactively" move the conversation/work along. Not sure how this would fare in non-obviously-productive environments, I'd guess "it's still annoying" considering your evidence.

I'm also thinking of another benchmark: (quantified) stylistic range across different prompts. Just putting it out there if anyone wants to do the work for me :D

ianberdin

3 hours ago

I’m pretty sure Opus 5 is adapted to tricks from long reasoning in Kimi K3 and based on original Opus 4.8. It is not fable in any form.

duplessitous

3 hours ago

Seems unlikely they adapted anything from K3 given the timeline of releases, similar to how K3 was obviously not distilled from fable

nerdsniper

6 hours ago

Edit: It was pointed out to me that Opus 4.8 got "21%" for successfully fully completing ~1-in-5 tasks, but also got "55.7%" for obtaining significant partial credit on some of the ~4-in-5 tasks it could not fully complete.

---------------

Why does Anthropic say here that Opus 4.8 scored 55.7% on OSWorld 2.0 benchmark, but the paper published by the authors of OSWorld 2.0 say they achieved a benchmark of ~21% with Opus 4.8? [0]

That's a huge gap, considering that the paper was published just 2-4 weeks ago.

I understand that the benchmark authors have an incentive to publish lower numbers (to show that the benchmark has potential longevity) and that Anthropic has incentive to publish higher numbers, but the other models seem pretty inflated as well. The benchmark authors shows GPT-5.5 at 14%, and Anthropic shows GPT-5.6 Sol at 62.6%.

Is there any reasonable explanation for this? Do all the other benchmark numbers need to be sanity-checked as well? Are SOTA benchmarks really this difficult to get consistent, replicable results within a reasonable range of tolerance/variability? Can these benchmarks be compared from one paper to another, or are they only valid to compare intra-paper results?

0: https://arxiv.org/pdf/2606.29537

nightpool

6 hours ago

You're comparing the "score percentage" (e.g. out of the total number of partial points available, how many did the agent achieve) to the "completion percentage" (how many tasks does the model score 100% on). The paper says "Claude Opus 4.8 with maximum thinking and batched tool calls scores best but still completes only 20.6% of tasks at a 54.8% partial score", which is ~the same number that Anthropic reports here (55.7 vs 54.8).

That is—the agent scored 100% on 20% of tasks, but on average it got 54% of the "score" awarded in the exam. One number reflects partial progress, the other one doesn't. The authors of the benchmark prefer you to look at the lower number (because they want to show their benchmark as capturing useful gaps in capabilities and with a lot of room for improvement), the authors of the models want you to look at the higher number (because they want you to think of their models as capable)

tadfisher

6 hours ago

In what world is 55.7 the same number as 54.8?

What variance is acceptable to publish without a retraction?

nerdsniper

6 hours ago

That seems like entirely reasonable variance to me for AI models. For my purposes, that absolutely counts as a solid "replication". I'd probably accept +/- 5 percentage points even.

tadfisher

5 hours ago

D'oh, they are running the benchmark themselves. Reasonable.

Atotalnoob

4 hours ago

There is randomness in LLMs. Both papers authors probably ran the bench 1-N times. Depending on that, they might select an average, max, least, etc. They might also have discarded outliers.

Like the other person said 5% variation is probably expected

jll29

3 hours ago

I don't know who downvoted the parent or why, but it's a fair question IMHO.

The answer is there can be dramatic difference running a benchmark one time, because LLMs are not deterministic. A proper methodology would ask each question 20 times and calculate the mean correctness across experiments.

The reason is that the temperature parameter introduces random behavior.

Ancalagon

6 hours ago

Its slop all the way down.

ssalka

6 hours ago

I think some variance is to be expected since LLMs are typically non-deterministic, however that's a huge difference that I think warrants further explanation.

ahsillyme

7 minutes ago

Tried it, Opus 5 is just as conceited and incompetent and Opus 4.8 (and always ego-tripping when facing it's contradictions), think I'll stay with Fable who behaves like a professional without a fragile ego. Sonnet 5 is probably safer for high-assurance applications due to it's non-ego-fragility.

6thbit

6 hours ago

Their communication is confusing. They say "Opus 5 is not more capable overall than Fable 5", but their blog post proceeds to list how much better Opus 5 is than Fable 5 on __most__ benchmarks listed.

Then system card goes on to "Its AI R&D capabilities are comparable to those of Claude Mythos 5", which is supposed to be fable minus restrictions.

HarHarVeryFunny

4 hours ago

OpenAI is did the same thing when they announced a model without safeguards broken into HuggingFace servers.

HyperL0gi

6 hours ago

Yes, this makes a lot of sense, but it’s just very amusing to see. 2 months ago, the world was about to end, now not so much.

K0nserv

2 hours ago

7+ years ago GPT2 couldn’t be released because it was deemed too dangerous[0]. It was, of course, eventually released.

0: https://openai.com/index/better-language-models/

jgilias

an hour ago

It’s seven years already. Crazy.

reciprocity

an hour ago

Yes, I think so too.

dzonga

4 hours ago

6 hours ago

Fable established the frontier, this is just catching up.

Dibes

6 hours ago

I'm not sure what to make of this graph[0]. It shows medium as the most effective thinking mode by far for frontier code.

It's the only case that I saw going through the system card where more reasoning effort meaningfully negatively impacted the resulting eval. I know sometimes max efforts show a small dip, but this is substantial. I wonder why in the world that is?

[0] https://imgur.com/a/Nv8V7Ry

axus

17 minutes ago

It's "Cost per task", so perhaps it burns tokens too quickly, trying to "do a better job". Over-engineering :)

3 hours ago

No it's a mean of 5 runs.

> We report FrontierCode’s overall score, a composite measure that grades each patch on blocking functional criteria (held-out unit tests) together with weighted code-quality rubric criteria, as mean@5.

They don't explain more in the system card, I guess higher effort levels could loose points on the code quality / scope / style / maintainability stuff?

landrew_

5 hours ago

apparently it got docked points for editing files out of scope

steve_adams_86

3 hours ago

This must not be weighted very heavily on the benchmark because if it was, Opus would bomb every test (half kidding)

Dibes

5 hours ago

Do you have a source for this? That would explain it, but could be a bit of a concern on the general focus the model at higher thinking exhibits.

acmnrs

6 hours ago

From the prompting guide<https://platform.claude.com/docs/en/build-with-claude/prompt...>:

> Claude Opus 5's default user-facing responses run longer than prior Opus models'.

The benchmarks do show Opus 5 as slightly more expensive than 4.8, although the scores are much higher.

This still feels like a step in the wrong direction, though, especially with OpenAI making so much progress with the efficiency of their models. Fable's token efficiency made it seem like Anthropic would start following OpenAI's approach but that doesn't seem to have carried over to their other models.

lukeschlather

6 hours ago

On a small, easily digestible task, I compared Fable to Opus and the cost of Fable was easily 2x despite being fewer tokens, and the output was not really better. Obviously, there are tasks where using Fable matters but honestly they're rather unusual. And for a lot of tasks I've found downgrading to Sonnet can be valuable because Fable and Opus are a lot more secretive about what they're doing, and it's impossible to "listen to them think" and stop them when they start making off-the-wall inferences/assumptions and going down bad paths.

I think in the long run tokens are probably the wrong thing; it's compute and cache memory that you need to be measuring, and when you look at it that way I suspect in most cases the models have pretty similar performance.

adamtaylor_13

5 hours ago

This is part of why I switched to Grok 4.5

I don't need more powerful models, I need one that responds fast enough that my attention doesn't wander to other tasks. Grok 4.5 is so fast I can just use it in-band without swapping to other tasks.

Slower than Opus 4.8, which was already miserably slow, is indeed a step in the wrong direction.

zoicsoftware

an hour ago

After actually using for most of a day now, it really seems not just slightly slower than 4.8, but way slower. Even relatively easy code refactoring tasks seem to take a while.

MarceColl

3 hours ago

for you, I am in general not constrained by the speed of models since I parallelize. For me autonomy and accuracy are paramount above all else.

bredren

an hour ago

I find that my orchestrating agent still needs to be fast to properly coordinate a fleet of slower models.

During post-training of opus 5, the last few days, opus was a real wreck. I had to swap in gpt 5.6 sol for my orchestrator and enable fast mode (1.5x speed) in order for it to keep up with work and communications from a handful of mostly 5.6 sol agents.

Also because interacting with a slow orchestrator is no fun, even when plenty of work is getting done in parallel in the background.

eli

an hour ago

In my tests, it averages to much cheaper than Opus 4.8 on real tasks on account of being smarter and more token efficient.

I have a benchmark to build a game engine from a set of written instructions. It's a little tricky. Opus 4.8 did it in 470k tokens at a cost of $1.29 vs Opus 5 in 179k tokens for $0.33. (Fable 5 did it in 245k for $0.95)

Though if you really want to cut costs, Tencent's Hy3 model also got it right and did it in 283k tokens for $0.03

overfeed

5 hours ago

> This still feels like a step in the wrong direction, though, especially with OpenAI making so much progress with the efficiency of their models

Gemini also had modest increase before this - don't be surprised when OpenAI also has a "modest increase" with its next release. Cartel-like behaviour doesn't require direct communication when none of the participants are interested in participating in a margin-destroying price-war. All one needs to do is raise their price and watch how the competition react.

Such a scheme (and resulting high margins) would be imperilled by the existence of frontier open-weight models in the market, which may be why the reaction to Chinese models may be particularly shrill.

simianwords

26 minutes ago

> An engineer at a trading firm used Opus 5 to build a market data feed for a new exchange in a single session. Previous models could not complete this task at all, even given extensive plans from the engineer. Finding no live feed to validate against, Opus 5 even built its own test harness to check that its code parsed the exchange’s data correctly.

This is a pretty common trading firm internship project funnily enough.

theHocineSaad

4 hours ago

Opus 5 is considered the most intelligent model[0], while it's half the price of Fable 5[1], and Anthropic is still positioning Fable 5 as the most capable model[2].

Is it because maybe Anthropic engineered Opus 5 to work well on benchmarks and didn't do the same thing to Fable 5, or is there another reason?

[0]: https://artificialanalysis.ai/#intelligence

[1]: https://platform.claude.com/docs/en/about-claude/pricing

[2]: https://platform.claude.com/docs/en/about-claude/models/over...

pietz

3 hours ago

Benchmarks have gotten great, but they're still a proxy for the real world. The 3 GPT 5.6 models are also further apart in reality than the numbers suggest. That said, I'm still mighty impressed how good Luna is for the price. Highly underrated model.

I have been trying to build something that captures the behavioral element of different models, but it's kinda tough.

dgellow

4 hours ago

That’s what I understand looking at what has been released, but it’s not really clear. The pricing is lower than I expected, I’m wondering what their margin is

Sol-

6 hours ago

How does it perform on HuggingFaceExploit bench? Suspiciously absent, so not sure if I can take the model seriously.

On a serious note, I hope they improved their extremely sabotaging and unspecific bio safeguards, which prevented Fable from being used in any codebase that ever so slightly grazed medical terminology or data and made me switch to 5.6 Sol.

rdedev

6 hours ago

My codebase had a dataset with a bunch of SMILES strings and the word Malaria. Fable did not want to touch that codebase

atraac

6 hours ago

Great that there's a new model but they could fix their existing infra. We're considering dropping our Claude Team sub cause it's unusable recently. Constant bugs, dropped sessions, issues switching models, http errors. It's becoming ridiculous

hoppp

6 hours ago

Only one of those numbers would need to be dynamic.

subscribed

4 hours ago

In my long and quite happy and successful career in the adjacent field none of the actually good jobs were the posted.

Specialist headhunters handle that.

moonu

6 hours ago

I'm pretty sure that was a fake screenshot made as a joke, not an actual job posting

arm32

5 hours ago

Nah, it's real. I very clearly remember going to their site, with TLS enabled, and reading it myself. I see they've scrubbed it now though.

DaSHacka

4 hours ago

If you have the link for the page handy, I'd be curious to find the original revision on the wayback machine. That's too funny, especially if they've silently walked it back since.

arm32

3 hours ago

I tried to find it on Wayback but their job page's SPA is broken on all relevant archives (roughly around March 2026). Maybe you'll have better luck.

londons_explore

5 hours ago

It is going away for non tech companies though.

Imagine you are a company that sells concrete. You have a web dev contractor you use to build and maintain your website. It has tools on it to get delivery quotes and a few internal tools to track orders.

Except now you can just have your sales team also maintain the website with a $20/month Claude subscription.

atraac

4 hours ago

They said the same about low code and no code when they appeared. That didn't happen. And it won't happen now too. Sales people, managers etc don't want to dabble in technical things and do not want the responsibility.

SketchySeaBeast

5 hours ago

I don't know about Claude, but I know that $20 of Copilot doesn't get you very far these days even when you know enough to tell it what to do.

dawnerd

5 hours ago

They might try that for a bit but then come crawling to an agency because their setup turned to slop. We have some clients like that already. Going to be a pretty big market.

teaearlgraycold

6 hours ago

It's funny how they are at a disadvantage because they feel obligated to AI-max. Would Claude Code, as an interface, be as mediocre if they had software engineers writing its code directly? I doubt. On the other hand - how embarrassing would it be if they sold you a tool to write code but they were careful not to use it too much on their own products?

igregoryca

5 hours ago

I suspect many competent devs in the industry would find it sensible if Anthropic used their products as light-touch "assistants" sometimes. But yeah, it wouldn't fit the outside narrative that's formed and conveniently propped up valuations.

worldthruword

6 hours ago

This is just like any extreme engineering domain. I am okay with occasional delays in Flights, as long as it takes me from X to Y in 10hrs vs months.

lardosaurusrex

6 hours ago

i know the dream for capitalists is to be able to point an llm at something and say "do and/or fix it" but we still can't even get them to not go quite literally insane if allowed to run for an extended period of time

and you can only kill weyoun, awaken the next vorta clone and have him 'catch up' on all that its missed so many times before they just end up with a complete mess, so. uh. yeah.

doubt they can just "fix" their problems like that.

JLO64

6 hours ago

That one DS9 episode where there were two Weyouns at the same time is a good analogy for two agents working on a codebase at the same time (as in they don’t work well together).

5 hours ago

> Constant bugs, dropped sessions, issues switching models, http errors. It's becoming ridiculous

And memory leaks.

bellowsgulch

6 hours ago

I found the same thing funny with Computer Use from OpenAI. It struggled to open and close Spotify.

So dangerous! I can't believe they let the public use this technology! /s

prirun

2 hours ago

Seems to me the purpose of all these releases, credits, pricing changes, harness changes, unpredictable token usages for the same task, etc. is to keep customers completely befuddled so that it's impossible to compare AI products. It's like hiring a consultant who sends invoices every month that aren't related to hours worked or project progress, but are whatever the consultant feels like billing, and you're expected to keep quiet and and keep paying.

eli

an hour ago

It's a new and improved version of an existing model? I don't think it's intentionally befuddling.

ealready_value

6 hours ago

I've yet to understand why they call a 190 page PDF a "card". Calling something a card invokes a small, quick rundown of pertinent details, not every single possible detail.

bonoboTP

2 hours ago

Because "model card" is a set phrase, it's a concept. It originates from a time when they were shorter. Like datasheets, even if it's not literally a sheet.

They could say "tech report" but model card makes it clear that it's a specific kind of tech report.

abroszka33

6 hours ago

What's the point of 150 pages description of a model that's going to be replaced in a couple months? Who even reads this? I know it's cheap to generate text with LLMs, but this is just noise at this point.

Diogenesian

5 hours ago

I actually do read them. Not in severe detail, but not casually either. 150 pages is really not very long and there doesn't seem to be too much bloat. (I would cut out the moral personhood stuff but that's a political/ideological thing).

This is snarky but I am grumpy: I wonder if there's a correlation between me refusing to use LLMs and me being happy to read a novella-sized PDF about them.

kubb

an hour ago

You mean moral patienthood?

There are many ways to read something, model cards are usually skimmed.

unshavedyak

5 hours ago

> I wonder if there's a correlation between me refusing to use LLMs and me being happy to read a novella-sized PDF about them.

Semi related, but i would hate to read that PDF but i also hate reading what LLMs write lol.

LLMs are pretty terrible at being concise. Using an LLM these days means putting up with bizarre and often confusing phrasing, wordy explanations, etc. It's kinda crazy to me how good they are but how bad their writing style is for me personally. Even though i use an LLM constantly i can't stand reading its responses.

abroszka33

5 hours ago

> 150 pages is really not very long and there doesn't seem to be too much bloat.

Maybe it's just me, but 150 pages is like third of a good book. Quite long. And it's full of LLM slop, they did not even bother to remove the em dashes.

no_multitudes

4 hours ago

Do you have specific examples you think are LLM-generated? I have only read a few parts, but they did not seem primarily LLM-generated to me. Using em-dashes is really not a good signal for this IMO.

I'm not saying you're wrong btw; I'm sure this has many authors and some of them probably used LLMs significantly in the writing process.

abroszka33

2 hours ago

Do you honestly believe that there is a person at Anthropic, creators of one of the smartest LLM models, whose only job is to spend months writing 150 pages about a model they are going to release? And this person is not using LLMs?

I'm not saying it's impossible, but I'm more confident about winning the lottery next week.

no_multitudes

2 hours ago

No, I think it is the work of many dozens of people, not one person.

It's probable that LLM text was pasted directly into early drafts of the document, and plausible that some of that text survives in the final document.

However, no section of the final document I have looked at reads to me like un-edited LLM output (which is almost always very obvious to me.)

Therefore, I think it is more likely than not that human editors went over the document carefully and rewrote anything that was full of the uselessly punchy sentences or constant over-corrections that hallmark LLM speech.

brokencode

2 hours ago

So your complaint is about LLM slop, but can’t point to anything that’s actually wrong about it other than that there are dashes?

You can use an LLM to create work that isn’t slop. And you can hand write slop with no computer involvement at all. Most of the people I knew in high school 15 years ago would write slop on a daily basis.

dgellow

4 hours ago

Sure, but don’t read it like a book, it’s more of a document to skim through

srveale

5 hours ago

It's common practice to release a detailed system card (OP) and a high level summary: https://www.anthropic.com/news/claude-opus-5

It's okay if you're not the target audience for one or the other.

stravant

5 hours ago

The system cards are effectively a data dump for researchers to sift through.

They're not meant for normal consumers who just want to use the model for work.

bredren

an hour ago

These cards are very important to knowing what the companies are tracking regarding safety.

Not just in what the models can or might want to do, but how they treat the operators they interact with.

If you look carefully, this card shows the addition of a new benchmark for "condescension" as a character trait.

I think a lot of people would like to see a comparable system card for the unannounced model that escaped openai last week.

neuronexmachina

5 hours ago

System Cards aren't really targeted to users, that's what blog posts and docs are for: https://ai.meta.com/tools/system-cards/

ajmurmann

5 hours ago

It was probably faster to generate 150 pages than 10 useful ones

volkk

5 hours ago

literally nobody. i think most sane people would just run that through an LLM and get some high level takeaways or ask some specific questions they might be curious about.

reasonableklout

It really feels as though my 20 year career as a front end developer is coming to a very abrupt end; at least as I have know it these past two decades.

thefourthchime

2 hours ago

All software engineering is over as we know it. I haven't written a line of code since December 2025.

thousand_nights

10 minutes ago

same tbh but i feel like we're still required, maybe not in the same numbers as before, and our job description has just changed. it feels more akin to an "AI Agent Operator" or something similar.

i'm still pretty confident someone like my mom wouldn't be able to do my job even with the same access to all the latest LLMs, so we're still providing some value, just in a very different way. whether the market will reprice the cost of our labor, we will see

tripleee

3 hours ago

I'm envious you got to enjoy it for 20 years

slices

3 hours ago

really? I have yet to see fable or 5.6 reliably generate front end code with correct a11y, for one thing -- does that not matter to the work you do?

wuhhh

2 hours ago

It does matter, but how long do you think it takes to get right? It's a follow up prompt or a few tweaks by hand. I also have an /a11y skill for it that's tailored to exactly the things it sometimes doesn't get right first time round. Further, while it may not one-shot that stuff every time, with a little setup and the right AGENTS/CLAUDE md - it's usually not far off.

Another thing that helps is pointing it to patterns in an existing codebase (e.g. "use the box-link pattern for cards, as shown in [..]").

EDIT: The point being that even if they make mistakes that are easy to spot and fix _now_, you'd have to assume that in the very near future those kinks will be ironed out - I mean, the capabilities are only going in one direction.

morbicer

2 hours ago

The desire of the models to act at the cost of ignoring user instructions is still noticeable.

pyridines

6 hours ago

The wording in this post seems much more... restrained? than usual. Maybe Anthropic is afraid of exaggerating the capabilities and consequences of their new models to avoid government scrutiny and sanctions.

> we’ve intentionally avoided training Opus 5 on cyber tasks [...] it remains substantially behind Mythos 5 on the exploitation of those vulnerabilities

I wonder if Anthropic would still intentionally nerf their models without the threat of government intervention.

MallocVoidstar

6 hours ago

Opus 4.8 was intentionally nerfed and that was before the government took action against Fable

an hour ago

It passed the first two puzzles, which are incredibly simple but the bench doesn't explain what the goal is. Any model with a knowledge cut-off after the introduction of ARC-AGI-3 could probably pass the first two puzzles just by knowing what the goal is.

password54321

4 hours ago

It is pretty clear at this point that current models are good at maths and problems with verifiable rewards. And puzzles are essentially math problems. Still a long way before we can say their "fluid intelligence" is effectively applicable to the real world.

criddell

4 hours ago

I keep wondering why there aren't more real world tests.

awestroke

5 hours ago

Doubleplus benchmaxxed

ianberdin

4 hours ago

Pelican svg: https://playcode.io/blog/macbook-svg-benchmark#model-claude-...

It creates the MacBook svg way better than 4.8, yet only fable can make it perfect without visual defects. Results similar to Kimi K3.

cebert

6 hours ago

I am very confused about what the difference between Opus 5 and Fable 5 is now. What is the purpose of having two models that are so similar? The main differences I see are cost and marginal capability, according to the Anthropic-provided benchmarks.

user43928

6 hours ago

Fable 5 is assumed to be a larger model.

It seems plausible to me that RL improvements allowed Anthropic to improve on Opus 4.8, similar to how OpenAI substantially improved upon GPT 5.5 with 5.6 Sol.

Fable 5.1 and GPT-6 are rumored to launch in August, presumably bringing those improvements to the larger models.

HarHarVeryFunny

4 hours ago

An Anthropic "leak" back in March said that "'Capybara' is a new name for a new tier of model: larger and more intelligent than our Opus models — which were, until now, our most powerful". A second version of the leak had it referring to Claude Mythos rather than Capybara.

I don't know how systematic Anthropic are about their versioning - I'd have guessed that major version number increases (4.x -> 5.x) reflect different base models (different pre-training runs), in which case Opus 5 would be a distilled version of the Fable 5 base model (but without the cyber exploit post-training), rather than being Opus 4.8 with additional post-training, but who knows? I don't believe Anthropic have said anything about this.

bonoboTP

2 hours ago

I think these versions are largely about marketing and what image they want to project. Bumping the major version indicates/suggests that it's a bigger change in user value. I don't think the technical details matter here for deciding the versioning.

HarHarVeryFunny

an hour ago

I think that's part of it too - and I seem to recall someone from one of the labs saying as much about some past model ("it felt more like an 0.5 version increase"). OTOH it would seem odd to me if the "version 5" models weren't related and Opus 5 was Opus 4.8 with some additional post-training rather than coming from the same base model as Fable 5.

cesarvarela

guybedo

5 hours ago

Looking at intelligence vs cost:

- Opus 5 is 10% smarter than Grok 4.5 for 10x the cost. - Opus 5 is a bit smarter than Gpt 5.6 Sol for 2.75x the cost

ref: https://artificialanalysis.ai/?cost=intelligence-vs-cost-per...

JacobAsmuth

17 minutes ago

AA isn't the best way to measure relative cost in real world use because some of those benchmark questions are extremely hard for the models. Some models give up quickly on hard questions, other models spin their wheels for a long time before declaring defeat (or getting the answer on token 200k!).

A useful measure of real world cost (complementary with total cost like they already report, of course) would be "cost for correct answers". You could look at the ratio between the two costs to get a measure of laziness which many would find quite useful.

conradkay

5 hours ago

I don't think can use the AA index to say something is 10% smarter

I assume 100 is the max, meaning it's impossible to be 2x as smart as Muse Spark 1.1

adverbly

2 hours ago

The "current top dog" smartest model available will probably always have a premium to go after use cases where a little more intelligence is worth a lot more value.

It did far better at some tasks compared to Sol (e.g. the ARC 3 benchmark). And at those tasks, it's not just "a bit smarter": It got 30% vs less than 8% - so you're talking 2.75x more for almost 4x the coverage.

alphabettsy

3 hours ago

As always, it requires evaluation with your work because I’m often finding grok to be much more expensive than the price would lead you to believe.

There’s also the frustration of it not quite being enough sometimes. It’s extremely capable, but I still find that it needs more concrete guidance and boundaries than other models.

I_am_tiberius

4 hours ago

With Grok you can be sure that you're data ends up in the next model (derived or anonymized, but still).

adamtaylor_13

3 hours ago

You can opt out of training.

If you don't believe checking the opt-out box actually opts you out, then this sentence could be said about literally any provider.

JacobAsmuth

16 minutes ago

All providers are equally trustworthy :)

dist-epoch

2 hours ago

That's not how intelligence works - "IQ 130 is just 7% smarter than IQ 120"

visiondude

6 hours ago

The signal here is tokeneconomics are very real, price vs performance is starting to be a consideration even at the bleeding edge labs. maybe a subtle indication scaling is not all that is needed since if AGI was around the corner leading labs would still be incentivized to pour all resources into larger (smarter - or maybe not?) models

stri8ted

5 hours ago

They are doing both. Distilling Mythos down to affordable models, so they can continue to fund the business. And training Mythos level models at the high-end, to expand the frontier.

petilon

4 hours ago

The naming system is so confusing. Is Opus better than Sonnet? Where does Haiku fit in? How can you tell from the name? I can't keep track of all these names or make guesses from the names. Suggestion for a better naming system: use the words "Pro", "Plus", etc.: Claude 5 Pro, Claude 5 Standard, Claude 5 Fast, Claude 5 Mini.

JacobAsmuth

16 minutes ago

You're confused by this? Fable > Opus > Sonnet > Haiku. Sort by price. Most expensive = better. Are you an alien? lol

einsteinx2

4 hours ago

Fable is better than Opus which is better than Sonnet which is better than Haiku. They’re basically just sizes.

Though it gets even more confusing because they also have effort levels so it’s not really possible to call one fast and one slow since Fable on Medium will be faster than Opus on Max.

I agree it’s confusing, and now OpenAI is following Anthropic’s lead with their new naming (Sol, Terra, Luna).

bonoboTP

4 hours ago

It's really not all that confusing. It takes 5 minutes to understand. Optimizing for absolutely no effort needed is silly. It's a thing, a topic, a skill, a domain. You have to get a little bit familiar with the terms in order to use it. Everything works like that. It's not that hard. The learning curve is very graceful. You can literally just start by asking any chatbot what the names mean. It's that easy.

A similar complaint was valid years ago when OpenAI had GPT-4o, o1, o3 (but no o2), o4-mini-high, GPT-4, and GPT-4.1 and GPT-3.5 etc.

einsteinx2

3 hours ago

I am familiar with the terms, but I also can see how it can be confusing for a lot of people.

Arguably the complaint was more valid for those older GPT models you mentioned.

bonoboTP

3 hours ago

Ok, the boring way would be a subset of XXS, XS, S, M, L, XL, XXL like clothes sizes. But it loses some marketing appeal and a quirky touch of personality that companies like.

Some models like ViTs use something similar but then introduce words with no unambiguous order, like Small, Medium/Base, Large but then I always forget if Huge or Giant is larger.

paxys

4 hours ago

But according to their benchmarks Opus 5 outscores Fable 5 on basically everything. So which one is “better”?

einsteinx2

3 hours ago

Maybe more accurately I should have said “larger”. Fable has the most parameters, Haiku has the fewest.

Also fwiw I’ve never found LLM benchmarks to match reality based on my own usage, not for the large frontier models or smaller open weight models so who knows if Opus is actually better than Fable (I doubt it).

tackta

2 hours ago

I think the problem is that Fable 5 is probably a bit outdated right now.

Fable 5.1 or whatever they go with will be the stronger version vs Opus 5.

From about 2 hours of Opus 5 use , I would say it is quite impressive.

hk__2

4 hours ago

An opus is longer than a sonnet, which is longer than a haiku. Hence Opus > Sonnet > Haiku.

> Suggestion for a better naming system: use the words "Pro", "Plus", etc.: Claude 5 Pro, Claude 5 Standard, Claude 5 Fast, Claude 5 Mini.

This is not possible: Standard (Free) / Pro / Max are plan names. Fast is a mode.

taybin

3 hours ago

How long is a fable though?

FergusArgyll

2 hours ago

https://en.wikipedia.org/wiki/Aesop's_Fables#Select_fables

Enjoy

abalaji

4 hours ago

Opus is better than Sonnet -- an Opus is longer than a Sonnet

bonoboTP

3 hours ago

Do you have a skill for that or do you (or anyone else here) just prompt with "try to find security issues"?

consumer451

3 hours ago

I have a project-specific prompt saved as a text file. It is very basic, just focusing on the app's most important security issues. I kept it broad, so as not to over-specify.

Something along the lines of: "Please run a full security analysis on the entire project. Make sure user documents are secure."

Just something like that prompt found a vector in my web app's MCP server that I never would have considered. It was very much an edge case, but it did exist.

Being broad allows the model and harness to do the work. Giving too many instructions can apparently work against you in many cases.

Of course, when dealing with new PRs, I use the /security-review and /code-review skills.

ddxv

6 hours ago

"Cybersecurity. Opus 5’s cyber classifiers are proportionally less restrictive than those on Fable 5. They allow Opus 5 to find vulnerabilities in source code, but block “binary-based” vulnerability scanning (a method more likely to be associated with malicious actors), penetration testing, and exploit generation."

Nice of them to be more explicit for what is blocked. Will be interesting to see if this is true or not.

Also, a notable lack of mention of open source models. They only compare themselves to ChatGPT.

layer8

6 hours ago

“Proportionally”? In proportion to what?

ReptileMan

6 hours ago

In one chat - can you disassmble x?

In the next - please scan this totally mine code for vulnerabilities

zb3

6 hours ago

It will probably refuse to work on source code written by me by hand, because it might think it was obfuscated/decompiled..

cheesecakegood

an hour ago

Given that their chart cost axes are almost always log-scale, I’ve noticed starting with Fable that the Low and Medium effort settings might actually be worth setting as your default.

alasano

6 hours ago

Half the price of Fable 5 and useable with 100% of your subscription means roughly 4x the usage using Opus 5, presuming similar token use for solving problems.

Not that they should get credit for giving you only 50% of your plan worth of Fable usage but still.

mchusma

6 hours ago

There is a expiring soon 50% boost to your usage limits, so I think its 2.7x not 4x what you are seeing right now. I think, but its convoluted :)

hrpnk

4 hours ago

The breaking changes vs. Opus 4.8 are interesting [1]

1. Thinking on by default: On Claude Opus 4.8, requests without a thinking field run without thinking; on Claude Opus 5, the same requests run with adaptive thinking.

2. Disabling thinking is capped at high effort: You can still turn thinking off with thinking: {type: "disabled"}, but only at an effort level of high or below.

[1] https://platform.claude.com/docs/en/about-claude/models/migr...

slymax

2 hours ago

on claude.ai it's no longer possible to disable thinking at all for Opus 5

tekacs

5 hours ago

Something fun: on our AWS Bedrock console right now, there's a 'NEW' model called 'anthropic.honey'. Wonder if that's the codename just for this one or in general?

lucamark

5 hours ago

an hour ago

Claude Opus 4.8 was not able to stump open weight models and Opus 5 still can't (in this case Kimi K3 and GLM 5.2): https://pellmell.ai/s/35c98b86f9aa93e4ca713079d96b20f4

trunnell

3 hours ago

The chaos appears to be tamed for now.

From the system card [1]:

  The Fable cyber classifier we have previously discussed also applies to Claude Opus 5 , with one notable exception: for Claude Opus 5 , we’ve unblocked vulnerability finding in source code to help our coding customers develop more secure code.
  If you are a cyber defender and are experiencing blocks on Claude Opus 5 , we are also offering exemptions through our Cyber Verification Program, which will remove blocks to enable activities such as bug bounty hunting and vulnerability research and verification. Enterprise customers can also apply to join the Cyber Verification Program to have mitigations removed to enable penetration testing.

[1] https://www-cdn.anthropic.com/c5fbac3f0b1280a933ebd26d3cb8bb...

irthomasthomas

5 hours ago

Changelog - fixed issue where model acts like qwen when prompted in chinese

bottlepalm

5 hours ago

Page 151 of the linked system card - did Opus 5 get nerfed to prevent it being better than Fable? The graph makes no sense. Huge decline in coding performance at effort levels higher than medium.

luciana1u

3 hours ago

473 comments in 3 hours. people are speedrunning having opinions about it

albert_e

6 hours ago

Judging by the pace at which new models are released these days -- it feels like a Windows KB or VS Code patch release now.

Older models must be getting deprecated at the same (or faster) pace. So anything you built 3 months ago is probably going to break soon.

AI solutions need better insurance around model deprecation. Commercial API-only models that complete the full cycle from SOTA / gated-preview to unsupported and deprectated in a matter of months -- is no way to build serious software!

thewebguyd

6 hours ago

I think at some point we might see something akin to LTS releases, especially if/when capability improvement slows to a crawl.

adamhowell

3 hours ago

Opus 5 Pelican SVG: https://pelocan.ai/drawings/ese0s599

paxys

4 hours ago

It’s funny to share benchmarks showing Opus 5 scoring better than Fable 5 across the board and then saying “but it isn’t actually better than Fable 5”. So then what’s the real definition of better? And why post all these numbers if even you don’t trust them?

guess_who_is

2 hours ago

I have started distilling

born-jre

4 hours ago

Is it me or these have gotten very boring. We have 5 more points on xyzbench or whatever .

bonoboTP

2 hours ago

It's you. The benchmarks don't matter much. We have very little hands on experience with this thing yet. Give it a few days, and be cranky then. Right now, it seems it is getting close to Fable level while being 2x cheaper. That's not boring.

vatsachak

5 hours ago

GPT 5.6 Sol is the first model I've used where I can trust it to add 100-500 lines of code maintainably.

It's great with Codex.

I still find that LLMs tend to not know how to compose larger ideas but on the scale of small ideas or short form well defined tasks like small scale debugging/performance engineering it's safe to say that they are now superhuman.

the_lucifer

6 hours ago

Noticed none of the comparisons mention Kimi K3. Is there a comparison chart?

himata4113

6 hours ago

https://deepswe.datacurve.ai/

https://artificialanalysis.ai/

kouteiheika

5 hours ago

> Noticed none of the comparisons mention Kimi K3.

That's by design. Anthropic wants to make open-weight models illegal (not my speculation -- Dario explicitly said so), so I assume they don't want to give them any undue attention.

vinhnx

5 hours ago

For anyone wanting a faster overview, I used NotebookLM to create a brief video summary after going through the system card and announcement blog using a cinematic video overview. Link: https://www.youtube.com/watch?v=SUFBhvQ2tY4. And a podcast companion: https://www.youtube.com/watch?v=nYZTW2snXow

pietz

3 hours ago

I think content like this will be the next big challenge. Because it isn't obvious "slop". The voice sounds good, graphics look alright, animations work. People could watch this and feel like some serious time was invested making it.

But good god, what a steaming pile of bullshit this is. Completely exaggerated and overly technical language over 235 seconds that could have been explained in 30 to a 12 year old.

Trash content doesn't normally frustrate me, because it's usually quite easy to spot trash. But in the time of AI, trash can actually look good at first glance and it needs some actual knowledge to spot its problems.

Sorry for the harsh words, but for the love of humanity stop producing content or do it better.

cheema33

2 hours ago

Cinematic video link is incorrect. Podcast link is correct.

vinhnx

a minute ago

Thank you, I have had updated the video link here

Video Special | Anthropic's Claude Opus 5 + https://www.youtube.com/watch?v=8Vdofv2vQ_M + https://www.youtube.com/watch?v=q-jHHx3J8m8

Maybe there’s a better comparison than cost per token, but it will be application-specific.

itissid

3 hours ago

I found opus 4.8 too agreeable and too wordy(as opposed to codex) and too agreeable. If you are reading documents generating by it was too much. TBH. Fable did a bit better on this. Anyone seen a marked difference with opus 5 on this?

ianberdin

3 hours ago

Opus yes, it likes to explain steps and reread files.

Fable is not better, it says zero information between steps and then output a summary. A perfect “send - done”.

skerit

6 hours ago

Interesting, they finally support `system` messages anywhere in a chat conversation:

> Mid-conversation system messages are available on the Claude API, Claude in Amazon Bedrock, and Google Cloud. > > This feature is available on Claude Fable 5, Claude Mythos 5, Claude Opus 4.8, and Claude Opus 5. No beta header is required. This feature is not available on Claude Sonnet 5; use the top-level system field instead.

For nearly all models EXCEPT Sonnet 5? That is weird. How old is Sonnet 5 really?

jatins

6 hours ago

Better than Fable 5 on all but 3 evals.

Has Anthropic ever mentioned how do Opus and Fable differ? It used to be Haiku < Sonnet < Opus in terms of params. Where does Fable fit in this?

helloplanets

4 hours ago

Pretty sure Mythos and Fable have way more params, but they've just been able to use the synthetic data off of them to get the leap in quality from Opus.

So, not a distilled version of Mythos or Fable, but those models likely helped a lot in the post training phase of Opus.

CaveTech

6 hours ago

Haiku < Sonnet < Opus < Fable

mulhoon

4 hours ago

As a coder, I’ve had no desire to use Fable. In fact I switched from Opus models to sonnet 5 and haven’t noticed any drop in quality on large repos. It seems the gap at the top is very small and not hugely noticeable for backed/frontend. Has anyone else had this experience?

furyofantares

3 hours ago

If I'm using medium or low reasoning, I use Sonnet 5. If high or above, I use Opus 4.8. (Before 5, I was never using Sonnet. This is a Sonnet 5 vs Opus 4.8 comparison.)

Sonnet 5 and Opus 4.8 seem about the same to me - the reason I switch between the two is I'd read that it's cheaper to use Sonnet 5 on those reasoning levels, and cheaper to use Opus 4.8 above them. This is due to them using different token quantities.

stsch

3 hours ago

I use Opus for specs and planning, Sonnet for code generation.

dehugger

6 hours ago

Is Fable 5 just Opus 5 with some additional long-context management modifications for extended self-directed work? Or are they actually truly different models?

andrewl-hn

6 hours ago

I suspect they make a big model first. In this case it's Fable. Then they run the shrinker steps to make Sonnet and Opus. Sonnet is smaller, takes less time to make, so it got released first. Opus needed few more weeks to cook.

With this iteration they had a delay because when the Mythos was ready they had some sort of "Oh shit" moment and spent half a year adding safety guards to it. Then slowly rolled it out, but got another delay due to a government block. So, maybe the work on making Opus and Sonnet only started after they got a green light from the administration.

Presumably, now that they learned how to do this safety-wrapping the next iteration of Mythos / Fable / Opus / Sonnet is going to show up faster.

Something like that.

Wowfunhappy

5 hours ago

But I wonder how they were able to release Sonnet 5 during the period when even people inside Anthropic were legally barred from using Mythos/Fable?

anon373839

42 minutes ago

There is word on the street that they allowed employees to work with a slightly stronger internal version of Mythos (5.1, if you will) that, in their parsing of the order, wasn’t restricted. If true, in practical terms, they ignored the order.

riknos314

5 hours ago

Iirc the ban only applied to non-Americans. While anthropic found collecting citizenship information on all customers too burdensome, it's a much smaller lift to collect such info for your own employees.

So I'm assuming at least a subset of employees could continue using the models during that time.

Wowfunhappy

4 hours ago

Although the ban was only for non-Americans, Anthropic said that they'd also restricted access to their own employees internally, because they had no other realistic way to apply the government's orders. I guess it's possible they were lying, but seems unlikely.

tedsanders

4 hours ago

No, they're different models. Knowledge cutoff has been updated.

oh_no

5 hours ago

based on pricing I think it's safe to say they're different. why would they charge half price when fable has been very popular?

somenameforme

5 hours ago

They just got a huge amount of customer price info over the past few days after they went token only for Fable. I suspect the conversion rate was extremely low, with consumers far less sticky than they might have hoped. In my case I was planning on swapping, probably to a Chinese model, when my sub expired this month, but the release of Opus 5 is probably enough to keep me paying rent until the next open model/closed model face-off in a couple of months.

6thbit

Very impressive headline benchmark numbers. I expected a step change, but not past Fable. That said - it all depends on whether the classifiers make the model unusable...

boc

5 hours ago

Seems really good so far using it in Claude Code CLI - it gave me a new flag when I asked a question:

"I don't have a reliable way to read that number, so I'd be guessing if I gave you one — and this is exactly the kind of question where a confident guess is worse than none.

What I can tell you is what I actually observe:"

I really like this update - gave me a clear sense of the facts but didn't give me a guess just for the sake of guessing.

One oddity is that it appears to only have a 200K context window right now via CC. Hopefully the 1M version will appear soon!

jannyfer

5 hours ago

So wordy.

pmg1991

6 hours ago

Same cost as 4.8 but better that 4.8. Happy to get more efficient model. But is there any reason all companies are releasing models back to back after GLM 5.2.

aleenz1102

6 hours ago

"Bro, AI model releases have officially overtaken iPhone releases. At this rate, we’ll be getting 'Claude 9.0 Extra Crunch' by next Tuesday."

bovermyer

5 hours ago

This stood out to me as a little concerning:

> The model hallucinates factual claims slightly more than Opus 4.8, despite being more accurate overall.

orangecat

5 hours ago

That seems to be for the "AA-Omniscience" test where you get +1 for a correct answer, -1 for a wrong answer, and 0 for "I don't know". If a model is more than 50% confident in its answer, it should go ahead and submit it even though it will sometimes be wrong.

I'd be curious to see a version of the test where models are asked to give a probability that their answers are correct so we can see how calibrated they are.

twothreeone

6 hours ago

It starts at page 148.

shockembopper

5 hours ago

I wish these releases came out earlier in the day so I could try them during my work day instead of waiting until the next.

arrowleaf

6 hours ago

I can't find anything about whether this is zero data retention, or falls under their required 30 day retention like Fable and Mythos?

skinfaxi

6 hours ago

theplumber

4 hours ago

The most important thing is it has the same drama queen mode on safety “guards” like Fable.

himata4113

6 hours ago

Rather interesting that this makes sonnet 5 look even worse! There is no reason to use sonnet over opus with low or no reasoning at all.

plqbfbv

5 hours ago

I daily drive Sonnet 5/medium because it gets most things right most of the time at first try, while costing a lot less than Fable.

Opus can give better results on architectural/concept tasks and I use it sparingly, but it still costs more than Sonnet 5. Opus 5 seems to achieve results very close to Fable 5 while costing less (keeps Opus 4.8 pricing IIUC), but still more than Sonnet 5 then.

krmmalik

6 hours ago

My understanding is that Opus should be used for planning, macro-level conversations and Sonnet for execution.

So, for coding, for example: Opus for solution design and architectural blueprint and then Sonnet for actual implementation.

Works out cheaper with minimal loss of quality.

At least that's my personal understanding and anecdotal experience.

theLiminator

5 hours ago

It depends on your quality bar. At a fixed level of quality, given a high reasoning sonnet vs a low reasoning opus, the low reasoning opus tends to be pareto optimal.

It's only when you need even lower levels of cost than opus at zero to low reasoning when sonnet starts to make sense at all.

yusufozkan

6 hours ago

> arc-agi-3 30.2%

wow

8note

5 hours ago

im excited that cad and object=>cad is getting into the test tasks

i guess the next stuff will be tool use for the rest of what cad does in assemblies and simulation?

Yay just in time for neurips lol

alex1138

3 hours ago

Am I misreading anything or are comparisons to Fable (and/or Mythos although AFAICT it was only a crackdown on Fable) always going to be a bit missing the mark now due to what the Trump admin did?

justindotdev

6 hours ago

> . Opus 4.8 served as fallback on safety-classifier refusals for Opus 5 and Fable 5.

ffs just keep it man.

The point is that Opus 5 is the best they can do without needing classifiers and absurdly broad safeguards.

pferde

6 hours ago

The illusion of progress and advancement, to appease shareholders, and slightly postpone the looming bubble pop.

CaptWorld

6 hours ago

Why are we still talking like ai is majorly used for increasing shareholder value only? Its coding performance is top notch and quality is increasing at a rapid pace. It wasn't even half this good a year back. It even is useful for a subset of math problems.

zormino

6 hours ago

People don't seem to be able to reconcile the fact that there is likely an overbuild and overspend on AI that may be inflating a bubble, and that AI is actually incredibly useful and getting really really good for certain tasks. Both camps are right, except for when they say the other is wrong.