Claude Fable 5 is here — and it's based on a model Anthropic once deemed too risky for the public

Anthropic has launched Claude Fable 5, its first public Mythos-class model. Previously deemed too risky for release, the model now includes stronger safety measures and conservative safeguards to prevent cybersecurity misuse. Fable 5 demonstrates exceptional performance in software engineering, vision, and scientific research, outperforming Opus models on complex tasks. It can work autonomously longer than any previous Claude model. Certain restricted topics will be handled by Opus 4.8 to ensure safety and prevent potential misuse.