Orchestration is the layer that decides the order in which models, tools or agents run, passes the result of one into the next, and stops or branches the sequence based on what comes back — the coordination, not any one of the calls being coordinated.
Microsoft’s Semantic Kernel framework documentation is explicit that orchestration is a separate layer from the agents themselves: “Semantic Kernel’s Agent Orchestration framework enables developers to build, manage, and scale complex agent workflows with ease”, describing a “unified interface” whose documented steps are to first define the agents, and then, verbatim, to “Create an orchestration by passing the agents” to it — the orchestration is what runs the workflow, not one more agent inside it. That is a specific vendor’s framework, not a universal standard, but the separation it describes — agents do the work, orchestration decides the order — holds regardless of which tools implement it.
That separation is also what makes a single tool call different from an orchestrated one. Anthropic’s own tool-use documentation describes one model deciding, on its own, when to call a tool based on the user’s request and the tool’s description — a single decision inside one model. Orchestration is what is needed once that decision has to span more than one model or agent: something outside any single one of them has to decide what order they run in and what each one is allowed to see of the others’ results.
Answering “can this customer get a same-day refund” can touch three separate systems in one turn: an order lookup, a policy check, and a refund-issuing call. The orchestration layer decides that order, passes the order lookup’s result into the policy check, and only calls the refund tool if the policy check clears — no single one of those three tools decides that sequence on its own.
See also: what is a multi-agent system, what is tool use in AI, what orchestration means in AI.
Building the layer that actually sequences calls across systems you already run is ai-integration-automation’s job.
