Anthropic introduced Claude Fable 5.1 and Claude Mythos 5.1, calling them the world’s most advanced models for coding and knowledge work. Fable 5.1 is built for long-running agentic tasks and research, with cache reads 75% cheaper than Fable 5—about 25% lower cost on typical workloads and up to 45% on highly agentic ones. Cursor reported 73.4% on CursorBench 3.2 at max effort.

Key Takeaways

  • ✓Fable 5.1 is generally available; Mythos 5.1 is limited to trusted cyberdefense and life-science access
  • ✓Cache-read pricing down 75%, cutting agentic workload cost by up to 45%
  • ✓Immediately live in Cursor and GitHub Copilot for long-horizon coding and research
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