Claude Fable 5.1 tops Agent Arena at $4.14/task median cost with +15.8% net gain
arena · x · 2026-09-06
- Agent Arena (LMArena) update: Anthropic's Claude Fable 5.1 (Max) takes the #1 spot with a +15.8% net improvement, redrawing the price-performance Pareto frontier — it is both the best-performing and the most expensive model, at a median cost of $4.14 per task.
- Scale: based on 6.7k+ real-world agentic sessions.
- By signal: implicit user sentiment (Praise vs. Complaint) at +42.5% — users praise it roughly 2x more than the next top model; Confirmed Success +22.4%; Bash Recovery +13.1%; zero Tool Hallucinations.
- The arena says traces for GPT-6 Astra are coming to enable comparison; users can contribute via Agent Mode.
Related event: Claude Fable 5.1 Tops Agent Arena Leaderboard(3 posts)→
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