RubyonrailsSep 2, 2026 ~1 min source read

Agents on Rails: Claude Fable 5.1 and GLM 5.3 Flash (formerly known as ox-alpha)

See how it handles real Rails tasks, and where it landed on the leaderboard today. Fable 5.1 scored as well as Claude Opus 5 on accuracy, but surpassed it in all other marks (including price!).

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See how it handles real Rails tasks, and where it landed on the leaderboard today.

Fable 5.1 scored as well as Claude Opus 5 on accuracy, but surpassed it in all other marks (including price!).

Fable 5.1 solved 58 of 63 runs (92%), matching Claude Opus 5 at the top of the leaderboard, and passed 20 of the 21 tasks at least once.

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The useful part

See how it handles real Rails tasks, and where it landed on the leaderboard today. Fable 5.1 scored as well as Claude Opus 5 on accuracy, but surpassed it in all other marks (including price!). Fable 5.1 solved 58 of 63 runs (92%), matching Claude Opus 5 at the top of the leaderboard, and passed 20 of the 21 tasks at least once.

How it works

Claude Fable 5.1: 58 of 63, $75 for all 63 runs, 5.4 minutes median per run.
Claude Fable 5:… Efficiency is the clearest difference between 5.1 and the previous generation: the bill is ~50% lower than Fable 5's and ~40%…

Details worth keeping

Claude Opus 5, the sole leader until now: 58 of 63, $120, 9.7 minutes.

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