arXiv AI

PartHackBench: Certified Equal-Progress Stress Tests for Partial-Credit Tool-Agent Evaluation

PartHackBench is a new methodology for evaluating partial-credit tool agents that eliminates confounding factors by using a private certifier to ensure that compared trajectories match in both current-state predicate satisfaction and standardized agent attribution. The approach measures score inflation only after certification, and in experiments on 18 held-out tasks it produced matched adversaries for 15 tasks, revealing mean inflation of 0.252 and detecting no strict rollbacks. The study shows that semantic LLM judges are vulnerable to evaluator-targeted attacks, whereas PB-CSTE current-state controls guarantee zero inflation by construction.

arXiv Computation and Language
3d ago

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
arXiv AI
5d ago

A Trust Layer for Agent Evaluation

The paper introduces a Trust Layer for Agent Evaluation, a post‑hoc framework that appends a belief flag to each benchmark score. It checks four properties: alignment with the benchmark’s grading logic, traceable computation of a passing answer, consistency between the agent’s claim and actual behavior, and stability across repeated runs. Applied to five agent configurations on 108 tasks, the study finds that only 22.6% of recorded passes satisfy all checks, revealing widespread issues such as untraceable computation, false completion claims, and unstable results.

By Mohammadreza Sediqin, Shivali Dalmia, Srinivasa Karthikeya Reddy Kovvuri, Abhishek Mukherji
arXiv AI
Sep 11

AgentAudit: An Open, Extensible Framework for Full-Lifecycle Trust Evaluation of AI Agents

AgentAudit is an open, extensible framework that evaluates the full lifecycle of AI agents, assessing planning, tool selection, execution, memory, and reasoning across ten dimensions such as instruction integrity, security, and alignment. Unlike existing benchmarks that focus on single aspects, AgentAudit analyzes the entire execution trace to attribute failures to specific stages. The framework was tested on five large language models, revealing significant differences in trustworthiness even among models with similar task‑completion performance.

By Shrey Nag, Sachita, Abhishek Kumar Singh, Lipi Goel, Rajeshwar Singh Janwar
arXiv AI
3d ago

The Harness as the Only Mutable Surface: Compliance-Bounded Self-Evolution of LLM Agents in Credit Pipelines, with a Measured Admission Gate

The paper proposes that self‑evolving large‑language‑model agents can only be safely reviewed if their changes are confined to the runtime harness—instruction text, tool‑call logic, and primitive composition—while the model weights remain fixed. A dual‑loop engine with an admission gate records a hash‑chained diff before deployment, and simulation experiments show that this gate admits only safe changes, preventing error increases and maintaining false‑positive rates. When the gate is removed, many harmful changes slip through and missed flags rise, illustrating the gate’s protective role.

By Ravil Akhtyamov
arXiv Machine Learning
Sep 30

Frozen Judges, Moving Agents: Version-Dependent LLM-Judge Error and the Limits of Judge-Assisted Agent Evaluation

The paper investigates how language‑model judges can make version‑dependent errors when evaluating upgraded agents. Using 35 public coding‑agent submissions, two customer‑service agents, and over a thousand expert‑labeled trajectories, the authors show that fixed judges often reject task‑conditioned error invariance and can incorrectly approve failed patches, especially as agent capability increases. Paired audits of current outputs reduce interval width only marginally, and the study concludes that independent human patch review is still necessary.

By Jiapeng Li
arXiv AI
Oct 2

VeriHarness: Scaling Agentic Verification for Long-Horizon Tasks

VeriHarness is a method that enhances verification for large language model agents tackling long‑horizon tasks without needing reference answers at test time. It transforms the base LLM into an agentic verifier by providing a workspace, evidence tools, and reusable verification skills, using disagreement resolution and consensus challenge to evaluate competing claims. Across five benchmarks and two frontier models, VeriHarness outperforms baselines, achieving significant performance gains and demonstrating self‑improvement of verification skills from failure feedback.

By Caiqi Zhang, Rujun Han, Zifeng Wang, Zoey CuiZhu, Nigel Collier, Tomas Pfister, Chen-Yu Lee
arXiv Machine Learning
Aug 31

VICT: Verifier-Instrumented Credit Tracing for Long-Horizon LLM Agent Reinforcement Learning

The paper introduces VICT, a method that leverages the internal structure of verifiable tasks to perform fine‑grained credit assignment for long‑horizon LLM agents. VICT exposes executable or evidence‑backed atoms from a task’s terminal verifier and traces them back to actions via dependency‑valid proof edges, redistributing advantage only along these edges. This approach improves performance on ALFWorld and WebShop compared to outcome‑only training and matches recent fine‑grained credit methods without requiring additional critics, labels, or inference‑time verifier access.

By Pengcheng Li, Zhengyang Zhang, Dongxu Zhang, Sui Huang, Shaohua Ma
arXiv AI
Aug 28

Invocation-Level Reliability of Tool-Using Agents

The paper investigates the reliability of tool‑using agents, focusing on two failure modes: selecting the wrong tool and constructing incorrect arguments. It introduces a correct‑invocation rate metric to distinguish these errors and evaluates five open‑weight models on multi‑step tasks up to depth 8, finding that by depth 6 about 70% of a model’s clean‑context capability is lost due to earlier mistakes. The study reveals that exact‑match scoring against a fixed gold trajectory forces severity and recovery parameters to extreme values, and proposes a conditional‑on‑state scoring remedy that yields more realistic severity estimates.

By Afiya Noorain, Subhranshu Mohanty, Amritesh Banerjee, Abhijit Dasgupta