Zunkiree Labs
AI Architecture

Function Calling

Definition

The mechanism that lets a language model invoke real code by returning a structured request instead of prose.

Function calling is how a language model triggers real work. The application gives the model a schema describing the functions available — their names, parameters, and types — and the model responds with a structured call naming the function and its arguments rather than free text. The application executes that function and feeds the result back. This is the bridge between a model that can only produce text and a system that can query a database, send an email, or book an appointment, and it is the foundation every tool-using agent is built on.