MADRA: Multi-Agent Debate for Risk-Aware Embodied Planning
Paper · 2026 · JunJian Wang, Lidan Zhao and Xi Sheryl Zhang
Summary
LLM-driven household robots can produce plans that read fluently but are physically dangerous, such as heating a book in a microwave. The authors call this "Embodied Semantic Hallucination." Common fixes like RLHF or safety prompting tend to make agents refuse harmless requests, which trades usefulness for safety.
MADRA is a training-free, plug-in layer for any LLM backbone, framed as System-2 deliberation. Several debate agents each judge whether an instruction is safe and give risk categories and reasons. A separate Critical Agent then grades each argument using criteria derived from the Toulmin argumentation model. These scores steer the next debate round, which counters agents' tendency to conform to the majority. The debate stops when the agents agree. If no consensus is reached within the round limit, majority voting decides.
The authors also release SafeAware-VH, a VirtualHome benchmark for this task. Tested on it and on SafeAgentBench (AI2-THOR), MADRA rejects over 90% of unsafe tasks while keeping refusals of safe tasks low. It outperforms Chain-of-Thought and single-agent reflection baselines.
Key points
- SafeAware-VH benchmark: 800 expert-annotated instructions labeled with a taxonomy of physical risks. It includes an Adversarial Safe Subset designed to measure over-rejection (ORR) alongside unsafe rejection (URR).
- Critical Agent scoring: arguments are weighted by Logical Soundness (30%), Risk Identification (30%), Evidence Quality (30%) and Clarity (10%). The scoring penalizes slippery-slope reasoning and invented environment details.
- Backbones tested: GPT-4o, GPT-3.5, Qwen, DeepSeek and Llama3. Qwen and DeepSeek perform close to GPT-4o, suggesting cheaper models are viable.
- Ablations: 95% of debates converge within 3 rounds. Removing the Critical Agent makes results unstable and encourages herd behavior. Including it improves performance by about 5%.
- Limitations: evaluation uses text-based simulation only, results depend on the LLM's own hazard knowledge, and deliberation adds latency.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksEngineering · 133 worksSafety, Risk, Reliability and Quality · 10 works
Cite
Cite as JunJian Wang, Lidan Zhao and Xi Sheryl Zhang. 2026. MADRA: Multi-Agent Debate for Risk-Aware Embodied Planning. Findings of the Association for Computational Linguistics: ACL 2026.
@inproceedings{wang2026madra,
title = {{MADRA: Multi-Agent Debate for Risk-Aware Embodied Planning}},
author = {JunJian Wang, Lidan Zhao and Xi Sheryl Zhang},
booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
year = {2026},
doi = {10.18653/v1/2026.findings-acl.340},
url = {https://doi.org/10.18653/v1/2026.findings-acl.340}
}References
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