Introducing Claude Fable 5.1 and Claude Mythos 5.1
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Anthropic is introducing Claude Fable 5.1 and Claude Mythos 5.1, two versions of the same model designed for coding and knowledge work.
Fable 5.1 is generally available and costs approximately 25 percent less than its predecessor for typical workloads, with even larger savings for agentic work. Mythos 5.1 is available only through limited access and has enhanced safeguards for cybersecurity and biology. The company's new Enterprise Frontier Safeguards allow customer data to be stored on the customer's own server infrastructure instead of Anthropic's. The models show progress in scientific research: Mythos 5.1 designed protein binders with ten times higher binding affinity than previous competition submissions, and Fable 5.1 created a new high-resolution elevation map of one-third of Venus.
They're the world's most advanced models for coding and knowledge work—and their research capabilities offer an early glimpse of how AI models will contribute to scientific progress.
Vibekollen prepared this summary with AI from the original publication. The content belongs to Anthropic.
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