AI Glossary / Function calling

Function calling (tool use) is a mechanism that lets a model use external functions: instead of guessing the weather, it calls a function that fetches the forecast; instead of describing an email, it calls a function that sends it. The model receives a list of available tools with descriptions and decides when and how to use them. This is the building block for creating agents and integrating AI with enterprise systems. The model doesn't execute code itself - it generates a structured call, and the application executes it and returns the result, providing control and security.