The first Mythos-class model Anthropic has made safe for everyone. State-of-the-art reasoning, vision and memory — and the longer the task, the further ahead it pulls.
Fable 5 is the first Mythos-class system released to the public — Anthropic's highest capability tier, built for sustained, multi-step work rather than one-shot answers.
Plans, executes and refines across many stages while holding context. Its lead over earlier Claude models grows as tasks get longer and harder.
multi-step agentsReads precise numbers from scientific figures, rebuilds a web app's source from screenshots alone — and beat Pokémon FireRed with a vision-only harness.
SOTA visionStays focused across millions of tokens in long-running tasks, taking and re-reading its own notes to keep improving its output.
1M contextThe old knobs — temperature, top_p — are gone. Instead, one effort dial trades depth for speed, from low to max.
effort: low→maxNew classifiers route high-risk requests; sensitive cyber/bio/chem queries get refused or handed to Opus 4.8. In testing, 95% of sessions stayed fully on Fable.
classifier routingUp to 128K output tokens, a 90% discount on cached prompt content, and native availability across enterprise plans and developer platforms.
128K outputFable 5 is state-of-the-art on nearly every tested benchmark. These bars animate to illustrate the widening lead as task complexity climbs — short prompts are close, long-horizon work isn't.
Drag the dial. Fable 5 replaces temperature & top_p with a single adaptive-thinking effort parameter — trading depth against latency and cost.
Medium effort. A balanced default — enough deliberation for most everyday tasks without paying for deep chains of thought.
Watch the read-head sweep the context window. Fable 5 sustains attention across long documents and tasks — and writes notes to itself to stay coherent.
Try a request. Fable 5's classifiers inspect intent: ordinary work flows straight through; sensitive cyber / bio / chem requests are refused or routed to the more conservative Opus 4.8.
Same underlying brain, different doors. The difference isn't raw capability — it's how each one responds to high-risk requests.
Fable 5 is available now to Claude Pro, Max, Team and Enterprise — and across the developer platforms you already use.
Start with Fable 5 →