Claude Fable 5.1 ships 45% cheaper, with a gated Mythos twin for cyber
Anthropic's new flagship is one model sold as two: Fable 5.1, generally available, and Mythos 5.1, gated behind trusted-access programs for cybersecurity and life-science work. The same upgrade cuts effective token prices by up to 45% on agentic workloads and adds Enterprise Frontier Safeguards, which keep customer data in their own cloud. In security, Fable 5.1 can now find vulnerabilities, though not weaponize them, with 60% fewer false positives.