Anthropic releases Claude Fable 5, a public version of its top Mythos model with hard safety limits

Anthropic’s Claude Fable 5 is a version of Mythos the public can access today

Anthropic opened its most powerful model family to the public for the first time with Claude Fable 5, a version of Mythos. It excels at software engineering, knowledge work, and vision, but blocks responses in high-risk areas like cybersecurity, biology, chemistry, and distillation, falling back to Claude Opus 4.8. Mythos was previewed in April for select partners only due to cybersecurity concerns. The post doesn't spell out Fable 5's parameter count, pricing, or regional availability.

Why it matters: Anthropic's first public release of a Mythos-tier model is a substantive product launch with explicit safety mechanisms. Cross-source cluster confirmed, all three HKR axes hit. Not scoring higher because the post doesn't disclose benchmark comparisons or pricing details.