Efficient LLM Safety Evaluation through Multi-Agent Debate

Dachuan Lin, Guobin Shen, Zihao Yang, Tianrong Liu, Dongcheng Zhao, Yi Zeng


Abstract
Safety evaluation of large language models (LLMs) increasingly relies on LLM-as-a-judge pipelines, but strong judges can still be costly to deploy at scale. We present a multi-agent judge that uses small language models (SLMs) in structured debates among critic, defender, and judge agents. To evaluate these systems, we introduce ForesightSafety Human-Annotated JailBench (FS-HAJailBench), a human annotated jailbreak benchmark with 11,100 labeled interactions spanning diverse attack methods and target models. FS-HAJailBench provides fine-grained ground truth for measuring both target-model robustness and judge reliability. On this benchmark, our SLM-based framework improves over matched small-model baselines and prior multi-agent judges, while approaching GPT-4o-level agreement with lower estimated unit cost. Ablation results show that three debate rounds provide the best accuracy-efficiency trade-off among the current Qwen3-14B variants. These results indicate that structured debate is a practical way to improve scalable LLM safety evaluation.
Anthology ID:
2026.emnlp-main.76
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1739–1755
Language:
URL:
https://aclanthology.org/2026.emnlp-main.76/
DOI:
Bibkey:
Cite (ACL):
Dachuan Lin, Guobin Shen, Zihao Yang, Tianrong Liu, Dongcheng Zhao, and Yi Zeng. 2026. Efficient LLM Safety Evaluation through Multi-Agent Debate. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 1739–1755, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Efficient LLM Safety Evaluation through Multi-Agent Debate (Lin et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.76.pdf