Bedrock is setup and works with models like global.anthropic.claude-opus-4-8 but fable does not work (global.anthropic.claude-fable-5). Data retention policy is correctly set on AWS as instructed here.
Thanks for the detailed report, and sorry for the trouble! Fable 5 launched very recently and isn’t available through AWS Bedrock yet — it currently runs via Cursor’s standard Anthropic connection, so global.anthropic.claude-fable-5 isn’t recognized as a valid Bedrock model. That’s what triggers the generic “Unable to reach the model provider” error. Your AWS data retention setup isn’t the cause.
Here’s my recommended steps to get quickly unblocked:
Use Fable 5 from Cursor’s normal model picker (with Bedrock toggled off for those requests).
Keep using Bedrock for the supported models — Opus, Sonnet, and Haiku — which is why Opus 4.8 works for you.
Hi Kevin, small correction with evidence: Fable 5 is live on AWS Bedrock right now. I called global.anthropic.claude-fable-5 directly and it returns real completions.
The real blocker is in Cursor. Through BYOK, AWS returns its own validation error:
Value null at 'toolConfig.tools.1.member.toolSpec.name' failed to satisfy constraint: Member must not be null (repeats tools.1..10)
