What is tool call?

A tool call is the model's structured request to run one operation the application defined, such as looking up an order, with typed inputs and a result the model reads before it replies. The model does not run anything itself. It emits something like "look up order 48213", the application executes the lookup against your system, and the result comes back into the conversation as text for the model to use.

It matters because tool calls are how an AI agent does anything beyond answering. Order status, subscription renewals, ticket creation, bookings and the handoff itself are all tool calls. Vendors package them under different names: Intercom says data connectors, Zendesk actions and integrations, Tidio Lyro Actions, and others say functions, skills or procedures. Under the names the mechanism is the same: a name, a description of when to use it, a list of inputs and a response.

Where the risks sit: the model chooses the tool and fills the inputs from the conversation, so the description of when to use a tool and the validation of its inputs decide whether a visitor can trigger it wrongly. Good designs keep inputs typed, escape visitor text before it lands in a URL or request body, limit which response fields the model may read, and never give the model a tool whose misuse cannot be undone. A refund tool is the standard example of one to leave out.