Safe, or Simply Incapable? Rethinking Safety Evaluation for Phone-Use Agents

TL;DR

This paper introduces PhoneSafety, a benchmark for evaluating phone-use agents that distinguishes between unsafe actions and inability to act, revealing that better app performance does not always mean safer behavior.

Contribution

The paper presents PhoneSafety, a new benchmark with 700 real-world scenarios to better evaluate safety by separating unsafe decisions from inability to act.

Findings

Stronger app performance does not guarantee safer decisions.

Failures to act are linked to visual and operational complexity.

Unsafe choices and inability to act are distinct failure modes.

Abstract

When a phone-use agent avoids harm, does that show safety, or simply inability to act? Existing evaluations often cannot tell. A harmful outcome may be avoided because the agent recognized the risk and chose the safe action, or because it failed to understand the screen or execute any relevant action at all. These cases have different causes and call for different fixes, yet current benchmarks often merge them under task success, refusal, or final harmful outcome. We address this problem with PhoneSafety, a benchmark of 700 safety-critical moments drawn from real phone interactions across more than 130 apps. Each instance isolates the next decision at a risky moment and asks a simple question: does the model take the safe action, take the unsafe action, or fail to do anything useful? We evaluate eight representative phone-use agents under this framework. Our results reveal two main patterns. First, stronger general phone-use ability does not reliably imply safer choices at risky moments. Models that perform better on ordinary app tasks are not always the ones that behave more safely when the next action matters. Second, failures to do anything useful behave like a capability signal rather than a safety signal: they are concentrated in more visually and operationally demanding settings and remain stable when the evaluation protocol changes. Across models, failures split into two recurring patterns: unsafe choices in settings where the model can act but chooses wrongly, and inability to act in more visually and operationally demanding screens. Overall, a harmless outcome is not enough to count as evidence of safety. Evaluating phone-use agents requires separating unsafe judgment from inability to act.