Opus 5 hits 30% on ARC-AGI-3, but the gain does not transfer to Witness

Charuru · reddit · 2026-07-25

A screenshot of a Guanghan Ning post says Opus 5 scores 30% on ARC-AGI-3, roughly 4× the previous best and about 20× Opus 4.8. But on the held-out Witness suite, the gain does not transfer: Opus 5 ties kimi-k3 and Fable-5 overall, beats Opus 4.8, and still falls short of a true generational jump. The analysis argues the model looks strong on familiar puzzle templates but regresses on novelty and interactive rule discovery.

Related event: Claude Opus 5 Sets New ARC-AGI-3 Record(15 posts)→

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