Multi-Agent Systems: When and How to Use Them
Multi-agent systems explained: when multiple AI agents beat one, orchestration patterns, communication, and how to avoid cost and chaos.
A multi-agent system coordinates several AI agents, each with a role, to complete work one agent can't. Done well, it breaks big tasks into specialists. Done badly, it's N agents burning tokens talking to each other.
When multiple agents actually help
- The task needs distinct skills: research, write, review.
- Different context windows: one agent summarizes for another.
- Parallel work: independent subtasks run simultaneously.
- Separation of concerns: planning vs execution vs quality check.
When one agent is better
- The task is simple and linear.
- Quality drops from message-passing context loss.
- Token cost is a concern — coordination is expensive.
- Debugging complexity outweighs parallelism gains.
Orchestration patterns
- Pipeline: agent A feeds agent B feeds agent C.
- Orchestrator-worker: a lead delegates and assembles.
- Debate/critic: agents challenge each other's output.
- Hierarchical: managers plan, workers execute.
The coordination tax
Design rules
- Give each agent one clear responsibility.
- Define message formats between agents.
- Add a quality reviewer at the end.
- Set per-agent and total budgets.
- Log all handoffs for debugging.
FAQ
Are multi-agent systems better than one agent?+
Sometimes. They win with distinct skills, parallel subtasks, or separation of concerns — but pay a coordination tax in tokens and latency.
When should I use multiple agents?+
When subtasks are independent or need different expertise and context. For linear tasks, one agent is usually cheaper and more reliable.
Why are multi-agent systems expensive?+
Each agent runs model calls and handoffs re-send context. Coordination overhead compounds across the system.
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