Group of 2 Nothing to try yet
claude-fable-5-1 is wired up with its own Vertex region, and fallback lists now gate on a fable51 check.
A new model id claude-fable-5-1 and its Vertex region constant VERTEX_REGION_CLAUDE_FABLE_5_1 were added. The opus/haiku fallback-list builders now check feature gate fable51 (replacing the previous fable5 check) before appending the model via WZe().
Names in the bundleclaude-fable-5-1
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Models overview touched a line naming claude-fable-5-1 after this was published.
| [Claude Platform on AWS ID](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | `claude-fable-5-1` | `claude-opus-5` | `claude-sonnet-5` | `claude-haiku-4-5` |models/overview see the edit
Confirmed since
Anthropic's documentation has since written up claude-fable-5-1, on Create Session.
- `BetaManagedAgentsModel = "claude-fable-5-1" or "claude-sonnet-5" or "claude-fable-5" or 11 more or string`api/beta/sessions/create see the edit
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up claude-fable-5-1, on Create Session.
Anthropic's release notes agree
Added Claude Fable 5.1 (claude-fable-5-1), now the default Fable model — 1M context, $10/$50 per Mtok with $0.25/Mtok cache reads