Willful Disobedience: Automatically Detecting Failures in Agentic Traces

AgentPex automatically detects procedural failures in agentic execution traces—wrong workflow routing, unsafe tool use, violations of prompt-specified rules—by extracting behavioral rules from agent prompts and checking entire execution histories against them. It catches critical failures that outcome-only benchmarks miss, making it practical to validate agent behavior at the workflow level.

Abstract

AI agents are increasingly embedded in real software systems, where they execute multi-step workflows through multi-turn dialogue, tool invocations, and intermediate decisions. These long execution histories, called agentic traces, make validation difficult. Outcome-only benchmarks can miss critical procedural failures, such as incorrect workflow routing, unsafe tool usage, or violations of prompt-specified rules. This paper presents AgentPex, an AI-powered tool designed to systematically evaluate agentic traces. AgentPex extracts behavioral rules from agent prompts and system instructions, then uses these specifications to automatically evaluate traces for compliance. We evaluate AgentPex on 424 traces from the τ^2 benchmark across models in telecom, retail, and airline customer service. Our results show that AgentPex distinguishes agent behavior across models and surfaces specification violations that are not captured by outcome-only scoring. It also provides fine-grained analysis by domain and metric, enabling developers to understand agent strengths and weaknesses at scale. The source code of AgentPex is available at https://github.com/microsoft/agentpex.