# PAC-BENCH: Evaluating Multi-Agent Collaboration under Privacy Constraints

arXiv: https://arxiv.org/abs/2604.11523 · HTML: https://mlsanity.com/paper/2604.11523/

## Key facts

- Cited by 7 papers in the map (data through 14 Oct 2026).
- Builds on 20 of its 45 references that are in the map.
- First posted on arXiv 13 Apr 2026.

## Builds on (most cited first, 20 of 20)

- [Judging LLM-as-a-Judge with MT-Bench and Chatbot Arena](https://mlsanity.com/paper/2306.05685/) (2023)
- [Generative Agents: Interactive Simulacra of Human Behavior](https://mlsanity.com/paper/2304.03442/) (2023)
- [G-Eval: NLG Evaluation using GPT-4 with Better Human Alignment](https://mlsanity.com/paper/2303.16634/) (2023)
- [Improving Factuality and Reasoning in Language Models through Multiagent Debate](https://mlsanity.com/paper/2305.14325/) (2023)
- [CAMEL: Communicative Agents for "Mind" Exploration of Large Language Model Society](https://mlsanity.com/paper/2303.17760/) (2023)
- [Multi-Agent Collaboration Mechanisms: A Survey of LLMs](https://mlsanity.com/paper/2501.06322/) (2025)
- [Auto-GPT for Online Decision Making: Benchmarks and Additional Opinions](https://mlsanity.com/paper/2306.02224/) (2023)
- [MultiAgentBench: Evaluating the Collaboration and Competition of LLM agents](https://mlsanity.com/paper/2503.01935/) (2025)
- [War and Peace (WarAgent): Large Language Model-based Multi-Agent Simulation of World Wars](https://mlsanity.com/paper/2311.17227/) (2023)
- [Hello Again! LLM-powered Personalized Agent for Long-term Dialogue](https://mlsanity.com/paper/2406.05925/) (2024)
- [Red-Teaming LLM Multi-Agent Systems via Communication Attacks](https://mlsanity.com/paper/2502.14847/) (2025)
- [Agents: An Open-source Framework for Autonomous Language Agents](https://mlsanity.com/paper/2309.07870/) (2023)
- [Optimization Methods for Personalizing Large Language Models through Retrieval Augmentation](https://mlsanity.com/paper/2404.05970/) (2024)
- [Privacy-Preserving In-Context Learning with Differentially Private Few-Shot Generation](https://mlsanity.com/paper/2309.11765/) (2023)
- [Self-Organized Agents: A LLM Multi-Agent Framework toward Ultra Large-Scale Code Generation and Optimization](https://mlsanity.com/paper/2404.02183/) (2024)
- [VillagerAgent: A Graph-Based Multi-Agent Framework for Coordinating Complex Task Dependencies in Minecraft](https://mlsanity.com/paper/2406.05720/) (2024)
- [Embodied Agents Meet Personalization: Investigating Challenges and Solutions Through the Lens of Memory Utilization](https://mlsanity.com/paper/2505.16348/) (2025)
- [REALM-Bench: A Benchmark for Evaluating Multi-Agent Systems on Real-world, Dynamic Planning and Scheduling Tasks](https://mlsanity.com/paper/2502.18836/) (2025)
- [ConVerse: Benchmarking Contextual Safety in Agent-to-Agent Conversations](https://mlsanity.com/paper/2511.05359/) (2025)
- [Terrarium: Revisiting the Blackboard for Multi-Agent Safety, Privacy, and Security Studies](https://mlsanity.com/paper/2510.14312/) (2025)

## Built on by (most cited first, 7 of 7)

- [Safe Multi-Agent Behavior Must Be Maintained, Not Merely Asserted: Constraint Drift in LLM-Based Multi-Agent Systems](https://mlsanity.com/paper/2605.10481/) (2026)
- [Selection-Invariant Communication Compilers for Privacy-Aware Multi-Agent LLM Workflows](https://mlsanity.com/paper/2609.26076/) (2026)
- [CoMemBench: Benchmarking Collaborative Memory Boundaries across Multi-Agent Workflow Topologies](https://mlsanity.com/paper/2609.32192/) (2026)
- [Policy-Backed Selective Regeneration under Tainted Inter-Agent Communication](https://mlsanity.com/paper/2609.26072/) (2026)
- [CoSec: Benchmarking Agent Security in Communities](https://mlsanity.com/paper/2609.34790/) (2026)
- [Loose Lips: Understanding Privacy Leakage in Agentic Dialogue](https://mlsanity.com/paper/2610.14071/) (2026)
- [Sanzaru: Benchmarking Protocol Formation under Epistemic & Communication Asymmetry](https://mlsanity.com/paper/2610.15163/) (2026)

## Abstract (arXiv)

We are entering an era in which individuals and organizations increasingly deploy dedicated AI agents that interact and collaborate with other agents. However, the dynamics of multi-agent collaboration under privacy constraints remain poorly understood. In this work, we present PAC-Bench, a benchmark for systematic evaluation of multi-agent collaboration under privacy constraints. Experiments on PAC-Bench show that privacy constraints substantially degrade collaboration performance and make outcomes depend more on the initiating agent than the partner. Further analysis reveals that this degradation is driven by recurring coordination breakdowns, including early-stage privacy violations, overly conservative abstraction, and privacy-induced hallucinations. Together, our findings identify privacy-aware multi-agent collaboration as a distinct and unresolved challenge that requires new coordination mechanisms beyond existing agent capabilities.