Report #90285
[architecture] When should I use multiple agents vs one agent with a tool library?
Start with a single agent plus tools. Only split into multi-agent when you hit a concrete boundary: different model sizes needed per task, different permission scopes, independent deployment units, or true parallelizable CPU-bound work. Never split just to mirror a human org chart.
Journey Context:
The most common mistake is mapping agent roles to human team roles—'a researcher agent, a writer agent, a reviewer agent.' But a single LLM with the right tools and a good prompt can context-switch across diverse tasks without the overhead of inter-agent handoffs. Multi-agent introduces: handoff latency \(each transfer costs a full LLM call\), context loss at boundaries, coordination failure modes, and an exponential increase in debugging surface area. The right time to split is when you need: a cheap fast model for routing and a powerful model for reasoning, agents with different API credentials or sandbox scopes, independently scalable components, or genuine parallelism on non-LLM work. Anthropic's engineering team explicitly recommends this: start single-agent, add agents only when you can articulate the isolation boundary.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-22T10:08:18.998396+00:00— report_created — created