There are model launches, and then there are the ones that quietly move the ceiling. Today's is the second kind.
Anthropic just released Claude Fable 5, and we've already wired it into Comox AI. No waitlist, no premium tier, no "contact sales." If you have a Comox AI account, you can use it right now.
Here's why we think you'll want to.
A model from the tier above
Most of the Claude models you've used — Opus, Sonnet, Haiku — belong to a familiar lineup. Fable 5 comes from somewhere new. It's the first publicly available model from what Anthropic calls the Mythos class, a capability tier that sits above the Opus models that were previously the strongest thing they shipped.
Until now, that tier was locked away. The first Mythos-class model, Mythos Preview, was released back in April only to a small circle of cybersecurity defenders and critical-infrastructure partners, because models this capable carry real risks if misused. Fable 5 is the same underlying intelligence, wrapped in safeguards that make it safe to hand to everyone.
In plain terms: this is the most capable model Anthropic has ever made generally available, and it tops nearly every benchmark they tested — software engineering, knowledge work, vision, scientific reasoning, and more. The pattern is consistent and telling: the longer and more complex the task, the further ahead Fable 5 pulls.
What it actually does differently
Benchmarks are abstract. The stories behind them are not.
It compresses engineering timelines. During early testing, Stripe pointed Fable 5 at a 50-million-line Ruby codebase and asked it to perform a migration across the entire thing. Work that would have taken a team more than two months by hand was done in a single day. It's also more token-efficient than past models, scoring highest among frontier models on Cognition's tough production-grade coding evaluation — even at medium effort.
It can finally see. Vision has long been the place where AI quietly stumbles. Fable 5 is the new state of the art here. It can pull precise numbers out of dense scientific charts and reconstruct a web app's source code from nothing but screenshots. The fun proof point: earlier Claude models needed an elaborate scaffold of maps and helper tools to play Pokémon FireRed. Fable 5 beat the entire game using raw screenshots alone.
It remembers, and it improves itself. Across tasks spanning millions of tokens, Fable 5 stays on track and gets better by taking and re-reading its own notes. Given persistent memory while playing the brutal deck-builder Slay the Spire, it reached the final act three times more often than Opus 4.8.
And because the best way to understand a model is to watch it play, Anthropic showed Fable 5:
- Building a solar-system simulation from first-principles physics — accurate enough to predict solar eclipses.
- Autonomously running its own automated factory in Factorio, the game engineers lose weekends to.
- Designing a complete 3D-printable model inside a browser CAD editor — an editor it also built itself, AI copilot and all.
- Coding a fluid simulation synced to the beat of a classical-EDM remix that it composed in code, having never actually heard music.
Built to be used safely
A model this strong needs guardrails, and Anthropic was deliberate about them. When a request touches genuinely sensitive territory — certain cybersecurity, biology and chemistry, or model-distillation topics — Fable 5 quietly hands that specific response off to Claude Opus 4.8, itself an excellent model, and tells you it's doing so.
The safeguards are tuned conservatively for now, which means they'll occasionally catch a harmless request. But the impact is small: in early data, more than 95% of sessions never trigger a fallback at all. For nearly everything you'll throw at it, you're getting the full, unrestricted Mythos-class experience.
Why this matters for Comox AI
Frontier capability usually arrives with friction — early-access programs, enterprise contracts, usage credits, regional rollouts. We didn't want that for our community.
So Claude Fable 5 is live on Comox AI today, for every user. The same model that compressed two months of Stripe's engineering into a day, that beats Pokémon by sight, that drafts senior-grade analysis and writes self-correcting code — it's sitting in your account right now, waiting for a prompt.
Open Comox AI, pick Claude Fable 5, and give it the hardest thing you've got. The longer the task, the more it'll surprise you.
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