Unsafer in Many Turns: Benchmarking and Defending Multi-Turn Safety Risks in Tool-Using Agents

Fuente: arXiv
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Main Authors: Li, Xu, Yu, Simon, Pan, Minzhou, Sun, Yiyou, Li, Bo, Song, Dawn, Lin, Xue, Shi, Weiyan
Format: Preprint
Published: 2026
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author Li, Xu
Yu, Simon
Pan, Minzhou
Sun, Yiyou
Li, Bo
Song, Dawn
Lin, Xue
Shi, Weiyan
author_facet Li, Xu
Yu, Simon
Pan, Minzhou
Sun, Yiyou
Li, Bo
Song, Dawn
Lin, Xue
Shi, Weiyan
contents LLM-based agents are becoming increasingly capable, yet their safety lags behind. This creates a gap between what agents can do and should do. This gap widens as agents engage in multi-turn interactions and employ diverse tools, introducing new risks overlooked by existing benchmarks. To systematically scale safety testing into multi-turn, tool-realistic settings, we propose a principled taxonomy that transforms single-turn harmful tasks into multi-turn attack sequences. Using this taxonomy, we construct MT-AgentRisk (Multi-Turn Agent Risk Benchmark), the first benchmark to evaluate multi-turn tool-using agent safety. Our experiments reveal substantial safety degradation: the Attack Success Rate (ASR) increases by 16% on average across open and closed models in multi-turn settings. To close this gap, we propose ToolShield, a training-free, tool-agnostic, self-exploration defense: when encountering a new tool, the agent autonomously generates test cases, executes them to observe downstream effects, and distills safety experiences for deployment. Experiments show that ToolShield effectively reduces ASR by 30% on average in multi-turn interactions. Our code is available at https://github.com/CHATS-lab/ToolShield.
format Preprint
id arxiv_https___arxiv_org_abs_2602_13379
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Unsafer in Many Turns: Benchmarking and Defending Multi-Turn Safety Risks in Tool-Using Agents
Li, Xu
Yu, Simon
Pan, Minzhou
Sun, Yiyou
Li, Bo
Song, Dawn
Lin, Xue
Shi, Weiyan
Cryptography and Security
Artificial Intelligence
Computation and Language
Machine Learning
Software Engineering
LLM-based agents are becoming increasingly capable, yet their safety lags behind. This creates a gap between what agents can do and should do. This gap widens as agents engage in multi-turn interactions and employ diverse tools, introducing new risks overlooked by existing benchmarks. To systematically scale safety testing into multi-turn, tool-realistic settings, we propose a principled taxonomy that transforms single-turn harmful tasks into multi-turn attack sequences. Using this taxonomy, we construct MT-AgentRisk (Multi-Turn Agent Risk Benchmark), the first benchmark to evaluate multi-turn tool-using agent safety. Our experiments reveal substantial safety degradation: the Attack Success Rate (ASR) increases by 16% on average across open and closed models in multi-turn settings. To close this gap, we propose ToolShield, a training-free, tool-agnostic, self-exploration defense: when encountering a new tool, the agent autonomously generates test cases, executes them to observe downstream effects, and distills safety experiences for deployment. Experiments show that ToolShield effectively reduces ASR by 30% on average in multi-turn interactions. Our code is available at https://github.com/CHATS-lab/ToolShield.
title Unsafer in Many Turns: Benchmarking and Defending Multi-Turn Safety Risks in Tool-Using Agents
topic Cryptography and Security
Artificial Intelligence
Computation and Language
Machine Learning
Software Engineering
url https://arxiv.org/abs/2602.13379