Glossary
Function calling (tool use)
How AI systems use your tools: APIs, databases and actions.
Function calling lets a model invoke defined tools: checking a calendar, querying a database, sending a message. You declare the tools (names, parameters, permissions), the model decides when and how to call them, and your code executes and returns results. It is the mechanism that turns language models from text generators into agents, and its safety comes from permission scoping.
Example from practice
A voice agent answers 'can I move my appointment?' by calling your calendar API, offering real alternatives, and booking the chosen slot: three tool calls in one conversation.
Related terms
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