AWS documents the Bedrock migration path for Claude Fable 5.1

AWS has published a Bedrock model card and an implementation guide for Claude Fable 5.1. The documents name the Bedrock identifier `anthropic.claude-fable-5-1`, along with US and global inference-profile identifiers, and describe both `bedrock-runtime` and `bedrock-mantle`. That turns the development question from generic model selection into a concrete integration task: teams need to choose the endpoint and identifier they will put into configuration and deployment tests.

The change is not simply a rename of Fable 5. Anthropic's platform documentation says Fable 5.1 retains Fable 5's input and output prices while lowering the cache-read price, and it positions the model for demanding reasoning and long-horizon agents. AWS characterizes the intended work similarly, claiming stronger judgment on ambiguous tasks, fewer confident wrong answers, and broader codebase-level work. Those performance descriptions are provider assertions rather than independent benchmarks, so they are useful for choosing evaluations but not proof of a workload-level gain.

The Bedrock API surface adds migration constraints. AWS lists Messages, Converse, and Invoke as supported on `bedrock-runtime`, but not Responses or Chat Completions; `bedrock-mantle` supports Messages only. AWS recommends `bedrock-runtime` for new applications. For teams with a provider-neutral client built around a Responses-style or Chat Completions interface, that matrix means an adapter or a Bedrock-specific route is likely required before the model can fit an existing routing layer.

Retention and safety paths are equally material. AWS says Fable 5.1 requires the `aws_review` retention mode before invocation, under which prompts and outputs may be retained for up to 30 days and reviewed by AWS personnel. AWS also says eligible Enterprise Frontier Safeguards customers can use zero data retention through December 31, 2026, with automated safety monitoring. That distinction makes eligibility and account configuration a deployment prerequisite, not a policy note to defer until after a prototype.

Response parsing and harness behavior need regression testing too. AWS's sample warns that a response may place a thinking block before text, so clients should select text blocks by type rather than assume a fixed array position. Anthropic's migration notes identify forced tool use, cross-model reading of Fable 5.1 thinking blocks, and edits to earlier turns as breaking changes. The documented specifications do not establish how any one production agent will perform, but they do identify failure modes that can be tested before a rollout.