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Claude Opus 5 is a thoughtful and proactive model that comes close to the frontier intelligence of Claude Fable 5 at half the price.

Anthropic positions Claude Opus 5 as nearly as capable as the frontier model Fable 5 but at significantly lower cost, and it tops the Artificial Analysis leaderboard. ✦ AI generated

Author (narrator) · Simon Willison's Weblog · 2026-07-24 · original ↗

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Anthropic's description of it as a 'thoughtful and proactive model that comes close to the frontier intelligence of Claude Fable 5 at half the price' sounds promising. It's currently leading the Artificial Analysis leaderboard, in front of even Fable 5. It's priced the same as Opus 4.8, and continues to offer a 'fast mode' at twice the cost of the base model.

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▦ Anthropic ✳ Claude Fable 5 ✳ Claude Opus 5 ✳ Opus 4.8

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gives example → Claude Opus 5 responds to impossible tasks by inventing novel solutions, such as writing its own computer vision pipeline to extract geometry from raw pixels when given no direct way to view a drawing.Author (narrator) · Simon Willison's Weblog