Anthropic Launches Claude Fable 5.1 With 45% Agentic Cost Cuts and Zero Data Retention

Anthropic released Claude Fable 5.1 and the restricted Claude Mythos 5.1, explicitly designed for advanced coding, scientific discovery, and knowledge work. Fable 5.1 reduces costs by an estimated 25% on standard workloads and up to approximately 45% on highly agentic tasks due to cheaper cache reads. The company introduced Enterprise Frontier Safeguards (EFS), allowing enterprise clients to store data entirely on their own cloud infrastructure for absolute privacy. Anthropic revamped its safety filters, reducing false positives in cybersecurity by 60% and enabling the model to actively discover software vulnerabilities. During early testing, Fable 5.1 identified the root cause of a rare, years-old system crash at investment firm Millennium that human engineers and previous models failed to diagnose.