Agent orchestration: coordinating several AIs around one task

What we are talking about

As soon as a task needs more than one model call, someone has to decide how those calls fit together. That is orchestration. It covers the order of steps, which model or agent handles each one, how results are passed along, how errors are handled and where a person signs off (human in the loop).

The most common patterns

Anthropic’s “Building effective agents” (December 2024) separates workflows, where models and tools follow paths defined in code, from agents, where the model directs its own process. It describes several patterns that have become reference points:

• Prompt chaining: one step’s output becomes the next step’s input.
• Routing: a first call classifies the request and sends it to the right handler.
• Parallelization: several calls work at once on independent parts, or on the same question to compare answers.
• Orchestrator-workers: a central model breaks the task down on the fly, delegates each piece and combines the results.
• Evaluator-optimizer: one call produces, another critiques, in a loop.

A concrete example

A company wants a weekly report on customer reviews. A coordinating agent splits the work: one sub-agent collects the reviews, three sub-agents analyse delivery, product and service feedback in parallel, and a final one writes the summary. The coordinator checks every part comes back, retries any that fail and sends the report to a manager for approval before it goes out. That split relies on explicit task decomposition.

Why it matters

Orchestration drives both the reliability and the cost of a multi-agent system. Every extra agent reads context and burns tokens; the agent cost calculator helps you estimate what a richer architecture adds. Protocols such as MCP and the A2A protocol cut integration work, but they do not make the design decisions for you.

Common myths

• “More agents make a smarter system.” Often they mostly make it pricier and harder to debug.
• “Orchestration always means one agent bossing the others.” A simple sequence hard-coded in advance is orchestration too, and often the most reliable kind.