Poster, NeurIPS 2026 workshop "Who Verifies the Agents?"
The Instrument Moves: Unrecorded Serving Changes in Agent Benchmarks
We pinned every control a mobile-agent benchmark exposes and ran ten repetitions. Ten and a half hours in, the pinned endpoint's behaviour changed, and no field a leaderboard records would have shown it.
- 10 of 10
- tasks that changed got worse
- −20%
- completion tokens per action, in one step
- ~8 pt
- gap two single runs need to exceed noise
