Definition
A multi-agent system is a system in which distinct agents communicate, specialize, coordinate, compete, or check one another to accomplish work. The agents may have different roles, contexts, models, tools, goals, or authority.
Multiple model calls do not automatically make a multi-agent system. There should be a meaningful separation of state or responsibility. A planner and executor with different contracts may qualify; three calls that extend the same conversation usually do not.
The architecture can add parallel capacity and specialization, but it also adds coordination cost, trust boundaries, and merge problems. Agreement between agents is not independent verification when they share the same model, evidence, or hidden assumption.
Distinguish it from nearby terms
An agent team coordinates distinct workers. A swarm often implies many locally interacting agents without one central planner. An orchestrator may coordinate multiple agents without being an agent itself.
Check your understanding
Three agents review a claim using the same source summary and the same model. Their unanimous answer is correlated repetition, not three independent checks.