Claude Fable 5 is 📝Anthropic's most capable generally available model — a Mythos-class system released on June 9, 2026 with a one-million-token context window and built-in safety routing.
Claude Fable 5 is the publicly available member of Anthropic's Mythos-class model family, sharing its underlying model with the less-restricted Claude Mythos 5. It uses the API model ID claude-fable-5, supports a 1 million-token input context with 128,000 maximum output tokens, and is priced at $10 per million input tokens and $50 per million output tokens — roughly twice the cost of 📝Claude Opus 4.8.
Anthropic describes Fable 5 as state-of-the-art across software engineering, knowledge work, vision, and scientific research. To make a Mythos-class model safe for broad release, Fable 5 automatically routes queries in high-risk domains — cybersecurity, biology and chemistry, and model distillation — to Opus 4.8, which Anthropic reports happens in under 5% of sessions. This safety routing is the central difference between Fable 5 and the less-restricted Claude Mythos 5.
At launch, Fable 5 was included on Pro, Max, Team, and Enterprise plans through June 22, 2026, after which access transitions to a credits-based model. It is available through the Anthropic API and 📝Claude Code, and descends from 📝Claude Mythos Preview, the restricted research model behind Anthropic's Project Glasswing security initiative.