Anthropic Launches Claude Fable 5.1 With Reasoning Lock

Anthropic released Claude Fable 5.1 on Tuesday, adding a lock on its own reasoning so new developer accounts can no longer rewrite a conversation’s history while keeping Claude’s stored thinking intact. According to BeInCrypto, the company also launched the restricted Claude Mythos 5.1 across Anthropic’s platform, Amazon Bedrock, Google Cloud and Microsoft Foundry. Pricing stays at $10 per million input tokens and $50 per million output, while cache reads fall 75% to $0.25 per million. Anthropic said typical workloads are 25% cheaper and complex agent tasks up to 45% cheaper.