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Claude Fable 5.1 reaches number one in Agent Arena with a 15.8 percent net gain

calendar_today September 6, 2026 person Arena domain aligned-news

Arena says Claude Fable 5.1 Max now leads Agent Arena, with a $4.14 median cost per task and a 15.8 percent net improvement. The result makes agent quality and per-task cost directly comparable.

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