Diversity Collapse in Multi-Agent LLMs

Every multi-agent system pitch assumes agents explore different solutions, but this paper shows they converge on near-identical outputs over time, even across different architectures and different starting prompts. The authors call it diversity collapse. The cause is structural coupling: shared context, shared task descriptions, and mutual feedback pull every agent toward the same attractor. They measure it formally with metrics like the Vendi score, and the homogenization is real. The practical consequence is that multi-agent setups for brainstorming, hypothesis generation, and ideation only work if teams explicitly engineer isolated reasoning phases, decoupled evaluation, and heterogeneous starting conditions.