Claude Fable 5.1 tops Senior SWE-Bench, matching Fable 5 at ~50% cost via Medium effort tier
ajratner · x · 2026-09-03
Claude Fable 5.1 now tops the Senior SWE-Bench leaderboard, edging out Fable 5 on the pass^3 tie-breaker (more consistently shipping quality code). Notably, its best effort tier is Medium, and combined with cheaper cache reads it matches Fable 5's performance at 50% of the cost — a lesson that medium effort is often all you need.
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