AI multi agent patterns · Interview knowledge

From 🧱 Your Multi-Agent Architecture Is a 2016 Microservices Diagram With the Boxes Renamed

- **Router.** A cheap classifier reads the request and forwards it to exactly one specialist, one hop with no synthesis step. - - Use for: support triage, intent routing in a product assistant, any case where the categories are known and the work per category is self-contained - - Router model: your cheapest one, a fine-tuned classifier, or a regex if the categories are clean enough - - Common mistake: letting the router “help” by adding context. It should classify and get out of the way - **Orchestrator-worker.** One capable model decomposes the task, dispatches subtasks to workers, and synthesizes the results. Workers are stateless, parallel, and can run on a different model than the orchestrator. - This is where the cost story lives: - - Orchestrator-tier and worker-tier models from the same vendor sit 5x to 15x apart on per-token price - - In a decomposed task, most tokens are worker tokens - - The number circulating in vendor write-ups this year is a 40 to 60 percent cost reduction versus running everything on the frontier model. Those write-ups are selling something, but the mechanism is sound - - Anthropic’s public data point: an Opus lead with Sonnet subagents beat single-agent Opus by 90.2 percent on their research eval. The same post reports multi-agent runs burn ~15x the tokens of a chat interaction, which is the other half of that ledger - Two rules for making it pay: - - Workers get a schema, an example, and a budget. Nothing else - - The orchestrator sees results, never raw worker transcripts, or your context bill grows with every worker you add - **Supervisor.** A loop rather than a fan-out. One model holds the plan, calls an agent, reads the result, revises the plan, calls the next one. - - Sequential and stateful. The supervisor’s context accumulates every result - - Use for: long-horizon tasks where step N depends on step N-1 (coding agents, migration tooling, multi-stage pipelines) - - Wrong for: anything parallelizable. It turns a 4-second fan-out into a 40-second chain

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