Anthropic will keep Fable 5.1 enterprise monitoring data in the customer’s own cloud later this fall
Anthropic on Tuesday made Claude Fable 5.1 generally available on AWS, Google Cloud, and Microsoft Azure, the company said. Input and output pricing stay $10 and $50 per million tokens, the same as Fable 5. Cache reads are 75 percent cheaper, $0.25 per million.
Mythos 5.1 is those same weights with more permissive safeguards for vetted cybersecurity and life-science work. It stays trusted-access only. The public API id is claude-fable-5-1.
A companion post the same day announced Enterprise Frontier Safeguards. Monitoring data will live in the customer’s own Amazon S3, Azure Blob, or Google Cloud Storage, under keys the customer holds. Customer employees review that data by default.
The enterprise move is customer-held logs so Anthropic can still correlate misuse across sessions, not a forever zero-data-retention wall.
In practice the monitoring files sit in a bucket the customer already pays for. A person at the customer reviews flags unless the customer opts into fully automated review. Customer-owned storage, customer-managed encryption keys, and fully automated review are each opt-in.
Anthropic’s stated reason for a 30-day retention window on Fable 5 is correlating misuse across sessions and accounts, not training. The company says it has never trained on enterprise data without explicit permission, and never will.
EFS ships phased, later this fall. Eligible customers keep zero data retention on Fable 5 and Fable 5.1 until then. Anthropic does not charge for EFS; cloud storage is billed by the vendor.
Anthropic says it built the product with more than 100 customers plus the three clouds, including a quarter of the Fortune 100 and every U.S. G-SIB. It will surface in Claude Code, Claude Enterprise, Claude Platform, Amazon Bedrock, Google’s agent platform, and Microsoft Foundry.
I keep the 30-day window on correlation, not training.
Fable is the public decoder: tighter safeguards, cheaper cache. Typical workloads cost about 25 percent less than Fable 5. Highly agentic workloads run up to about 45 percent less.
Mythos is the same model in a smaller room. Claude Security, the enterprise scanner that finds vulnerabilities and suggests patches for a human to review, now runs on Mythos 5.1.
Zero data retention until fall is the bridge. The product is the logs they can still search.