AI Judge changed title after evaluation, original title: "Anthropic launches Claude Fable 5, its first public Mythos-class model"
Anthropic has cleared its first Mythos-class model for broad public access, delivering Claude Fable 5 as the company's strongest generally available option yet for extended agentic work in coding, knowledge tasks, and tool use while keeping the same base architecture as the more restricted Mythos 5 variant.
Claude Fable 5 is out today. The first Mythos-class model everyone can use & the first model I hand off whole projects to. This weekend I built a self-maintaining, proactive media tracker for myself, over 2 days with Fable taking large chunks at a time
Tables shared in launch posts place Fable 5 ahead on agentic coding, knowledge work, and tool-use metrics compared with Opus 4.8 and competing models like GPT 5.5, though full official model card details live on Anthropic's site.
High-risk prompts involving cybersecurity, biology, or model distillation automatically fall back to Opus 4.8 with user notification and no token charge; reroutes remain under 5 percent of sessions and data is kept for 30 days.
Positive users praise Claude Fable 5's creative outputs and benchmarks while negative users criticize Anthropic for hidden limits, gatekeeping, and dishonest releases.
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.
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
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.
I just got bullied by AGI
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.
Brilliant idea! Next up: Apple randomly reboots your Mac if you're building competing tech, Gmail silently edits your email if you mention rival platforms, and Tesla Autopilot swerves if it detects you're working on self-driving cars.
All in the name of safety, of course. Because malicious actors controlling the world’s operating systems, inboxes and cars would be extremely dangerous!
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
Fable 5 is now available in Claude Code and Cowork
Fable is the best model I have used for coding, by a wide margin. It is a big step up, enabling less prompts and steers, more efficient token use, better code quality, better tool use, more intelligent self-verification, longer running sessions, and higher trust & autonomy.
Happy coding!
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.
Actually it's fine guys! I figured out a way, see below.
Claude Fable 5 is a great model afterall, and I also finally appreciate the difference between CLAUDE.md and AGENTS.md.
It's all good.
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
DO NOT USE FABLE 5 FOR AI R&D/CODING!!
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
I am curious how Anthropic makes images for their promotional materials. Is it just Claude collaging found images? It doesn't look like an image model.
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.
Holy shit they actually launched it
@claudeai It's agi guys.
Turns out Fable 5 is shadowbanning AI researchers 🫤
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
If you thought AI progress was slowing down, well here's the immediate answer to that. Huge jump in capability across the board. This is going to deliver major improvement in agents across almost all knowledge work categories.
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.
LMFAO this can't be real
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
@claudeai let the monthly migration from codex to claude code begin
June 9th Researcher Reciprocity License
"if you train on it, you let us generate - reverse terms of use void"
Status quo 1. We teach frontier devs with ICLR/NeurIPS papers, OSS Github contributions 2. They use it to make frontier models 3. Then ban us from exploring our ideas
We need a new license, original thinkers can't be an underclass to a tyrannical researcher fiefdom
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
Claude Fable 5 is also an amazing biology model! It just ran an autonomous drug design loop. 14 protein targets. No human. 9/14 (64%) yielded promising candidates.
This is quite remarkable that a model identifies binding sites, runs bioinformatics pipelines, and recovers from its own failures.
That's not a benchmark. That's a drug discovery engine. The 10x acceleration in AI-enabled drug discovery is well underway! 🔥🔥
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.
trust & your brand is a long term thing being in the frontier is a short term thing
note that the nerfing here is SILENT. meaning anthropic will SILENTLY NERF and give you WORSE ANSWERS without alerting you
that's honestly demonic
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
We consume data we did not create. We inherit tools we did not invent. We run on chips we did not make. But when the commons bears fruit, we fence it.
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
First they came for the model builders...
I feel we're getting a glimpse of a future where AI is only provided to a privileged few, and that's not a future I want to live in.
mythos will be bad ON PURPOSE on ai "frontier llm research" tasks, this is very very sad for the research community
also the fact that this is un purpose not visible to the user is crazy
My favorite chart from our system card - FrontierCode is an excellent eval, and it accurately reflects the step up I feel when using Fable!
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.
AI Judge changed title after evaluation, original title: "Anthropic launches Claude Fable 5, its first public Mythos-class model"
Anthropic has cleared its first Mythos-class model for broad public access, delivering Claude Fable 5 as the company's strongest generally available option yet for extended agentic work in coding, knowledge tasks, and tool use while keeping the same base architecture as the more restricted Mythos 5 variant.
Claude Fable 5 is out today. The first Mythos-class model everyone can use & the first model I hand off whole projects to. This weekend I built a self-maintaining, proactive media tracker for myself, over 2 days with Fable taking large chunks at a time
