Fable 5.2 tops Agent Arena at 1.6x Opus 5.5's score, but critics note it was measured at max effort

Anthropic's top model, Claude Fable 5.2, took first place in Arena's Agent Arena, which ranks models on real user tasks.

Arena said on Nov. 11 that Fable 5.2 (Max) posted a +30.4% net improvement across 4,700 real agentic sessions, about 1.6 times the No. 2 model, Opus 5.5 (+19.5%). Gemini 4 Carbon was third (+17.0%) and GPT-6 Astra sixth (+14.5%). Fable 5.2 also ranks first in Code, Chat and Work. Fable 5.1 had been fifth (+14.8%).

Arena also published cost. Median cost per task was $7.30 for Fable 5.2, above Opus 5.5 ($5.50) and GPT-6 Astra ($6.00) and about five times Gemini 4 Carbon ($1.50). API pricing is $8/$40 per million input/output tokens, 20% below Fable 5.1.

Pushback came quickly. "That #1 is Fable 5.2 at Max effort. Medium is the default in Claude apps and Claude Code," one user wrote. Another said Opus 5.5 is "all-around the best and cheaper" and the gap shows only on very complex, long-running tasks. On r/ClaudeCode, a post titled "13 minutes of work with Fable 5.2 to reach the 5-hour limit" made the day's top list.