Claude Fable 5 Model Support / Claude Code v2.1.170

What

Claude Fable 5 is now a supported model in Claude Code, positioned as the most capable option for the hardest and longest-running tasks.

Usage

claude --model fable
claude --model claude-fable-5

Details

Alias fable (and fable[1m] for 1M context) resolve to Fable 5
Full model IDs: claude-fable-5 (firstParty, vertex, foundry, gateway), anthropic.claude-fable-5 (Bedrock/Mantle)
Context window: 64k default output / 128k max — same as Opus 4.8
Default effort level: high (same as Opus 4.8)
Fable 5 appears at the top of the /model picker for eligible accounts
A companion model, claude-mythos-5, is also registered internally for the safety-refusal fallback lane
The /model command's help text now reads: "Provide an alias for the latest model (e.g. 'fable', 'opus', or 'sonnet') or a model's full name (e.g. 'claude-fable-5')."

Evidence

Model ID registration and picker entry (search for "claude-fable-5" and "Fable 5 · Most capable for your hardest and longest-running tasks")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Claude Fable 5 Model Support