Anthropic Launches Claude Fable 5.1 and Mythos 5.1: Better Coding, 75% Cheaper Cache

Anthropic has launched two upgraded Claude models: Fable 5.1 for general use and Mythos 5.1 for trusted organizations in cybersecurity and life sciences. Cache read pricing drops 75% from $1 to $0.25 per million tokens, cutting typical workload costs by 25% and up to 45% for highly agentic tasks.

Fable 5.1 scores 55.8% on Terminal-Bench 4.0, up from 42.0% for Fable 5, and reduces false interventions by 60%. Both models are available through Claude API, Amazon Bedrock, and Google Cloud Vertex AI.