“independent agents amplify errors 17.2x through unchecked propagation, while centralized coordination contains this to 4.4x.”

A controlled study across 180 configurations with prompts, tools and budgets held fixed. Multi-agent setups helped decomposable tasks (+80.8%) and hurt sequential planning (−70%). Returns turned negative once a single agent already scored above about 45%. This is the best evidence yet for deciding what to fan out at planning time.