Same model, wildly different results: Fable 5.1 shines in Claude Code but stumbles elsewhere

altryne · x · 2026-09-21

altryne compares Fable 5.1 across coding agent harnesses and finds dramatic differences: in Claude Code the model documents requests in Linear, proactively offers to kick off jobs, and opens a PR in 22 seconds — while in other (unnamed) harnesses it behaves like "the slow kid." His takeaway: the harness around a model can matter as much as the model itself. He also laments running out of Fable tokens.

Related event: Hands-On: Fable 5.1 Crushes Astra in Coding Agent Tests(3 posts)→

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