
Anthropic Launches Claude Fable 5, Its Most Powerful Public Model Ever
On June 9 Anthropic released Claude Fable 5, a 'Mythos-class' model that sits above the Opus tier and is state-of-the-art on nearly every benchmark it tested. In early use Stripe reported the model compressed a codebase-wide migration that would have taken a team over two months into a single day. Because raw Mythos-class cyber and bio capabilities are dangerous, Fable ships with classifiers that quietly route risky queries to Claude Opus 4.8 instead, triggering in under 5% of sessions; a locked-down twin, Mythos 5, goes only to government cyber-defenders. It matters because Anthropic is now putting frontier capability in everyone's hands while openly conceding it had to wrap it in guardrails to do so safely.



