Anthropic has made Claude Fable 5.1 generally available on Amazon Web Services (AWS) for all customers. ^[1] Anthropic announced the availability of Claude Fable 5.1 on Amazon Bedrock and the Claude Platform on AWS today. ^[2] Anthropic released Fable 5.1 and Mythos 5.1, twin versions of its most advanced AI model. ^[3] Anthropic, an AI safety-focused research firm valued at $965 billion as of its latest funding round in May 2026, has announced the launch of Enterprise Frontier Safeguards (EFS). ^[4] Anthropic announced the launch of Enterprise Frontier Safeguards (EFS), a solution that combines zero data retention (ZDR) with safeguards for detecting misuse, storing data in customer-controlled cloud infrastructure. ^[5] Anthropic has designated Claude Fable 5.1 as a Covered Model, which carries additional data retention, safety review, and access policies. ^[6] Anthropic reports that Claude Fable 5.1 is a clear improvement over Fable 5 on the hardest reasoning tests, including competition mathematics and graduate-level questions in engineering and the sciences. ^[7] Because Claude Fable 5.1 is a Covered Model, its use is subject to data retention for up to 30 days and human review by Amazon personnel. ^[8] Fable 5.1, the unrestricted version, is available on cloud platforms or through the Anthropic API. ^[9] Mythos 5.1 will only be available to registered Anthropic partners engaged in cybersecurity or life sciences research. ^[10] The Fable 5.1 release includes changes meant to reduce token cost and false-positive restrictions from the model's safeguards. ^[11] In the EFS implementation, customer data is stored in cloud infrastructure managed entirely by the enterprise rather than Anthropic. ^[12]