Tool Use / Function Calling

Applications

Simple Definition

The ability for AI models to call external functions, APIs, or tools to retrieve information or take actions beyond their training data.

Full Explanation

Function calling allows LLMs to interface with the real world. The model is given descriptions of available tools (e.g., 'search_web(query)', 'get_weather(city)', 'send_email(to, subject, body)') and decides when to call them. This is how ChatGPT plugins work, how AI agents retrieve current information, and how enterprise AI integrates with business systems.

Related Terms

AI Agent

An AI system that can autonomously take actions, use tools, and complete multi-step tasks without human intervention at each step.

Structured Output

Constraining an AI model to generate responses in a specific format (JSON, XML, etc.) for reliable programmatic processing.

Last verified: 2026-03-30← Back to Glossary