Anthropic on June 9 released Claude Fable 5, the first publicly available version of its top-tier Mythos line, just days after the company warned that frontier AI is becoming too dangerous. The model excels at software engineering, knowledge work and vision, and Anthropic says it underwent more than 1,000 hours of jailbreak stress-testing before launch.
Fable 5 ships with hard safety limits: in high-risk areas such as cybersecurity, biology, chemistry and distillation it blocks responses and falls back to Claude Opus 4.8. All usage carries a mandatory 30-day traffic retention to help defend against novel attacks. Pricing is $10 per million input tokens and $50 per million output tokens, double the cost of Opus 4.8.
Through June 22 the model is included at no extra cost in Pro, Max, Team and seat-based Enterprise plans; from June 23 it will require usage credits. A more capable sibling, Mythos 5, is being deployed only to organizations already approved for the advanced model.