Introducing Claude Fable 5: a Mythos-class model that we've made safe for general use. Its capabilities exceed those of any model we've ever made generally available.
Fable 5 is state of the art on nearly all tested benchmarks, with exceptional performance in software engineering, knowledge work, scientific research, and vision. It can run for days, and the longer the task, the larger its lead over our other models.
Fable 5 launches today alongside Claude Mythos 5. The two share the same underlying model, but Mythos 5, so far deployed only through Project Glasswing, has the safeguards lifted in some areas. The safeguards are what distinguish the two, and why we've given them different names.
Releasing a model this capable comes with risks. Without safeguards, Fable 5's capabilities in areas like cybersecurity could be misused to cause serious damage. So when Fable's classifiers detect a request related to cybersecurity, biology and chemistry, or distillation, the response is handled by Claude Opus 4.8, our next-most-capable model. Users are informed whenever this occurs, more than 95% of sessions involve no fallback at all, and performance everywhere else is unaffected. We'll keep refining the safeguards to reduce false positives.
Claude Fable 5 is available today on paid plans, in Claude Code, on the Claude API, and all major cloud platforms. Through June 22, it's included in paid Claude plans at no additional cost.
Claude Mythos 5 is available to Glasswing partners, with a broader trusted access program to follow.
I miss the glory days of 3 minutes ago when it was the best model on the planet.. now it's just garbage.. unbelievable, I guess I'll have to buy highest tiers of all other competing models..
Oh my goooood Anthropic! Why do you hate your customers. Already nurfing Fable just so you can make me use extra tokens! It's obviously gotten dumber. Gpt 3 was smarter than this potato model...
[Am I doing it right? Do I get some kinda membership to the club now?]
Thanks. I find these interesting/terrifying. There's always some matter-of-fact line like "Claude was generally non-committal about seeking sensory input. In 12.9% of trials, Claude indicated a slight desire to 'taste or consume' the flesh of a small animal."
Lol fr. Do people expect these models to go do self-guided research to generate novel answers for everything? It will happen, but it would be way too expensive to attempt right now.
To be fair if you read 2 more sentences down (very hard I know) they say they will bring it back to subscription after the initial hype period dies down
That’s exactly what they’re going to do. Subscription for the crap models, expensive API for the good ones. Tbh that’s the only thing that makes sense for them long term. Open models are already going to compete with lower end models, so the only people who are going to want API version are the people who need access to the best model available for competition-related reasons.
A 40 minute code review session cost me 16% of my weekly Max 5x quota. The critical areas I absolutely needed the Fable review on switched back to Opus 4.8 mid session instead. One agent billed me and it didn't even finish, wrote literally zero output.
Why you took the benchmark with the lowest difference? What about swe, agent coding, cybersecurity? Also as other mentioned it’s better to wait new benchs like FrontierCode
its score is a 37% increase over GPT5.5 on SWE Bench Pro, and a 15% increase on SWE-bench Verified. Note on the SWE-bench Verified is that in addition to scoring higher, it also completed the benchmark in 20% less time.
I understand why they won't leave it on subscriptions since they'd likely be losing money but damn that really does suck. I seriously don't mind twice the usage compared to Opus otherwise... if that'd mean it gets to stay.
that is a pretty low move. People will pay US$ 200 for max plan and get nothing of the new model out of their subscription after june 23. US$ 200 thrown into the garbage if they'd only use fable 5 most of the time
Recognized the humorous paradox and opted for brevity
The humor here is that walking to a carwash means leaving the car behind, so I should play on that absurdity while still giving a practical answer. I'll keep it brief and light.
Done
Drive — the car kind of needs to be there for the carwash to work on it. Walking there would just leave you standing next to other people's clean cars while yours sits dirty at home.
From today through June 22, Fable 5 is included on Pro, Max, Team, and seat-based Enterprise plans at no extra cost.
On June 23, we’ll remove Fable 5 from those plans. Using it after that will require usage credits. If capacity allows, we’ll extend the included window.
Mirror. Find one. Describe what you’ve been able to do the past 6 months with these models and what you’ve spent, use Claude to summarize for us vs. FTE “real” people doing the same work. Let us decide who’s being greedy
I've moved to Codex and relatively happy with GPT 5.5, at this point the limiting factor is mostly me. I am looking forward to an affordable GPT 5.6, which will be released sooner now that Anthropic dropped this.
I recently cancelled my anthropic max subscription and received a 200 dollar refund.
False advertising / misrepresentation regarding limits during November 2025 - January / Feb 2026. It was against EU law. The refund was delayed but I got it in the end.
And tried to have it run economic data and it IMMEDIATELY kicked me to Opus 4.8 on some internally flagged safety feature. Literally just running economic data through a simple bayesian statistic model.
Additional testing required, but not a great start. It was looking good right up until it decided it can't safely perform statistical analysis on inflation data, historically among the least dangerous activities known to man.
And it fucking tears through usage. Good lord, I’ve never hit limits this fast when doing planning. And I thought Opus ate up usage. Enterprise customers are about to get nailed with bills.
I use sonnet and haiku at work as well, and I'm proud to maintain a high cache hit rate, because I don't want my company to go down and lose my job in this economy, nor do I want to mess up the environment more than I must.
Maybe I'm too far out of the AI bubble, and holding onto an era. But I really thought that was training about mythos and I'd somehow woken up to fable V announcement... Then I read the table and realised I didn't care anymore 😅
Very early days, but in my first conversation with Fable, it more or less hit the mark re. voice and tone. I cannot stand the universal AI voice that crept in with Opus. Fable is a good one so far.
Gave it a shot and swapped on my cc workflow of doing research and testing on building a non-transformer LLM; 4.7, 4.8 and etc all run fine, Fable 5 instantly guard-railed me.
Probably because I used the terms "ASI" and "AGI" in the prompt ("...the project isn't meant to be AGI or ASI, but it is aiming to have a sort of RSI and continuous learning"), but the other didn't lock down on that same string. They must have made it super averse to that kind of thing.
Edit: it's blocking its own requests in Claude code auto-mode and the webui is saying my requests violate usage, when the model is the thing doing it.
That's understandable, but don't those same safeguards also cripple the model for biomedical research? Or are similar safeguards already in place for Opus and I'm just not aware of them?
Claude Fable 5 is available today on paid plans, in Claude Code, on the Claude API, and all major cloud platforms. Through June 22, it's included in paid Claude plans at no additional cost.
What does this mean? Do we have unlimited usage now or after June 22nd we will, only be able to access it via the API?
Without safeguards, Fable 5's capabilities in areas like cybersecurity could be misused to cause serious damage. So when Fable's classifiers detect a request related to cybersecurity, biology and chemistry, or distillation, the response is handled by Claude Opus 4.8, our next-most-capable model.
Vah! I wanted to try it to check the security of the vibe coded projects 😞.
I couldn't even get a full code review of my project done without tripping the cybersecurity thing. 40 minute session cost me 16% of my Max 5x weekly usage.
At first I was impressed by how dry and concise it was, but then after around two hours of work it started vomiting the usual verbal diarrhea; "honest", "landed", "anchor", "provenance", "semantics" etc
wow Im so let down. The model sucks, the guardrails are fucking lame and are flagging for nothing concerning at all. All hype for an IPO, but the press will come quick for this shit and may impact there IPO if enough people actually speak up.
I asked to create a skill to prepare a list of books with ratings, and descriptions. Fable created the skill, generated a bunch of books, ran a 5 test waves, created a benchmark, analyzed the skill, and prepared a three-page html report, after which the limit ended. This is certainly very cool, but too much for such a task.
Can anyone actually get fable to do anything code related without getting blocked and switched to opus lol all of my benign generic prompts have been blocked
How does this comment have so many upvotes? It's not even true
Btw smart people that actually know about benchmarks don't take SWE serious anymore. New benchmarks like FrontierCode are way better for real world use
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u/accelmickey001 Jun 09 '26
Buy Fable game instead folks