Anthropic is essentially competing against itself at the top of the AI leaderboard. Claude Opus 5 Max, released on July 24, 2026, has secured the number two position on Agent Arena’s rankings, sitting just behind Claude Fable 5, which is also an Anthropic model.
Claude Opus 5 High, a slightly less compute-intensive variant, grabbed the number three spot.
What the numbers actually show
Agent Arena, hosted at arena.ai, evaluates AI models on real-world agentic tasks using crowdsourced assessments and causal inference across five core metrics tied to real user tasks involving tool orchestration.
Claude Opus 5 Max posted an 11.88% net improvement score, a 17.56% confirmed success rate, and a praise versus complaint ratio of 25.63%, the highest on the leaderboard.
