Model
claude-fable-5.1
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Anthropic releases Claude Fable 5.1 and Claude Mythos 5.1
Anthropic's launch table put Fable 5.1 ahead of its own Fable 5 and Opus 5 and OpenAI's GPT-5.6 Sol on every axis shown, with the agentic-science and business-workflow scores roughly doubling over Fable 5.
Models & capabilities · Benchmarks & progress
Claude Fable 5.1 solves a 370-year-old cipher in a Vals AI test
Given only the puzzle, Anthropic's model recovered the plaintext of Sir Thomas Urquhart's unsolved 1653 cipher in 44 minutes and 176,000 tokens, then checked its answer against the couplet's own structure.
Models & capabilities · Benchmarks & progress