Splitting a task across more agents also splits decisions that used to sit inside one agent's head.

Adding agents to a coding task moves decisions into the gaps between them.

That's where these teams break.

A study of 1,902 AI coding agent runs found one task passing 9 of 10 runs at 2 and 4 agents.

At 8 agents, one step each, it failed all 10.

A single rule about rounding fell between two of them.

In smaller teams one agent held both sides and settled it alone.

Split apart, neither owned it, and the teams raised it in every failed run without agreeing.

A prompt line saying "you are the coordinator" builds no structure in an agent team.

Before adding an agent, ask which decision you're pushing into the gap between two of them.

– arxiv. org/abs/2608.16801

Title: "When Agents Coordinate: Measuring Coordination in Multi-Agent AI Coding"