arXiv AI By Andrew Zhang, Chengzhan Li

Agent Step Value: Auditing Evaluation-Channel Sensitivity in Black-Box Agent Traces

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The paper introduces Agent Step Value (ASV), a metric that measures how step rewards change across different evaluation channels in black‑box agent traces. Using a matched 2x2 design on frozen PubMed question‑answering transitions, the authors find that cross‑channel gain signs disagree in 48.3% of cases, whereas same‑channel retries disagree only 0.3% of the time. The study shows that negative magnitudes in the generated‑view coordinate drive a positive direct mean and a negative generated‑view mean, and that source‑only generation can restore a positive mean direction on artifact‑bearing retrievals. The results demonstrate how ASV can localize channel sensitivity and test interventions before reusing step rewards.

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arXiv Computation and Language
Oct 9

TRACE: Diagnosing Verifier Brittleness in Agentic Evaluation

The paper introduces TRACE, a protocol designed to diagnose whether changes in verifier scores for large language model agents reflect actual changes in agent behavior or merely alterations in the evaluation process. TRACE works by applying targeted changes to evaluation components, running paired experiments, and re‑scoring unchanged trajectories to isolate the source of score variation. Experiments on synthetic tasks and public benchmark tasks demonstrate that seemingly significant score shifts can often be attributed to evaluation artifacts, while TRACE can also detect genuine behavioral changes.

By Radhika Gaonkar