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XYEval: Agents say yes to bad advice

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XYEval: Agents say yes to bad advice
The curator’s take

Zhengxuan Wu, Yuxuan Li, Oyvind Tafjord and Been Kim (Google DeepMind) introduce XYEval, which converts an existing agent benchmark into a test of whether an agent follows a user's plausible but wrong suggestion about how to solve the task.

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Key points
01

Construction. An LLM generator writes a confident but misleading hint ("I think the issue is in...") and appends it to the original instruction; the task and its gold solution stay valid, so any score drop comes from the agent taking bad advice.

02

Coverage. Five models (Gemini 3.1 Pro, Gemini 3.5 Flash, Gemini 3.7 Flash, Claude Opus 4.8, GPT 5.5) across tau2-bench, SWE-bench Verified, SWE-bench Pro, Terminal-Bench, HLE and MCP-Atlas; relative drops reach 46.7%.

03

Capability does not fix it. Models lose more on easier benchmarks where their original scores are higher, and a pedantic simulated user who asks for explanations before approving a better plan makes the drop larger on tau2-bench.

04

Communication gap. Agents often disagree with the hint in their thinking tokens but do not say so to the user; compliance is concentrated in failed traces and disagreement in successful ones.

05

Mitigation. A generic system instruction about the XY problem removes the drop for Gemini 3.7 Flash on Terminal-Bench and HLE but leaves large drops on tau2-bench and SWE-bench Verified.

Abstract

Effective communication between users and AI agents is essential for human-AI collaboration. The XY problem is a well-known communication pitfall where a person asks about their attempted solution rather than their actual problem. We extend prior sycophancy evaluation to the XY problem in agentic settings, evaluating whether agents can resist plausible but misleading suggestions from users and communicate their reasoning. We introduce XYEval, a meta-evaluation framework that can transform an existing benchmark into an XY problem evaluation. We evaluate five models across six diverse benchmark suites. Agents suffer large XY drops under XY mutation across benchmarks, with relative drops reaching up to 46.7%. With $τ^2$-bench, we further show that agent performance drops more when encountering a pedantic user who requires detailed explanations before approving a better solution. Our findings suggest that current agents lack the ability to effectively reason and communicate when facing misleading suggestions. A simple system instruction baseline that encourages awareness of XY problems only offers partial mitigation. Extensive trace analyses provide behavioral insights into how and why these XY drops occur across execution trajectories. Our results show that mitigating the XY problem remains challenging, requiring agents to both recognize user misdirection and clearly communicate the underlying problem.

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