Function Calling in LLMs: Complete Guide with Examples

Published 2026-07-16

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Overview

Master LLM function calling (tool use). Syntax, best practices, supported models, and real-world code examples in Python and TypeScript.

Key Topics

This article covers the following topics related to function calling, llm tool use, ai function calling:

  • Core concepts and terminology
  • Practical implementation guide
  • Best practices and common pitfalls
  • Comparison with alternatives
  • Real-world use cases

Getting Started

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FAQ

What is function calling in LLMs?

Function calling allows LLMs to invoke external functions or APIs, enabling them to access real-time data and perform actions.

Which models support function calling?

OpenAI GPT-4, Claude, Gemini, and most modern LLMs support function calling with varying syntax and capabilities.

Conclusion

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Frequently Asked Questions

What is function calling in LLMs?

Function calling allows LLMs to invoke external functions or APIs, enabling them to access real-time data and perform actions.

Which models support function calling?

OpenAI GPT-4, Claude, Gemini, and most modern LLMs support function calling with varying syntax and capabilities.

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