Multiple agents are justified only when distinct roles improve the workflow. If one agent can complete the task with fewer handoffs, a multi-agent design may add cost and failure points without adding value. Start by defining the goal, the roles, and the decision that each role owns.
Use structured messages rather than passing unrestricted conversation history between agents. Decide which agent owns state, how conflicts are resolved, and when a human must approve an action. Add limits on retries, loops, tool calls, and token usage. Every handoff should have a reason that can be inspected later.
Testing should include missing information, contradictory recommendations, failed tools, and malicious instructions in retrieved data. Measure quality, latency, cost, and completion rate together. Begin with two agents and one workflow, then compare the result with a simpler baseline. Complexity should be earned by measurable improvement.