Getting Started with OpenAI Function Calling

Function calling allows GPT models to output structured JSON that calls your functions instead of writing free-form text.

Why it matters

It's the cleanest way to integrate GPT with your existing code. Instead of parsing model output, you get structured data you can act on directly.

Basic example

{
  "name": "get_weather",
  "parameters": {
    "location": "São Paulo",
    "unit": "celsius"
  }
}

Define your function schema in the API call, and GPT will call it when appropriate.