Where is the actual function in Assistant function calling?

Really struggling to figure out function calling. When attempting to build a function in the Playground assistants, the example looks like this:
{ "name": "get_weather", "description": "Determine weather in my location", "parameters": { "type": "object", "properties": { "location": { "type": "string", "description": "The city and state e.g. San Francisco, CA" }, "unit": { "type": "string", "enum": [ "c", "f" ] } }, "required": [ "location" ] } }
But there’s no actual code or API reference here. How do I specify what the function should call?

Hi @mikea

This is just a json schema describing the function, it’s not the function definition. The schema helps model know before hand what function(s) is/are available to the model and how to call them, should it need to.

Here’s the sample response for function call, now a subset of tools, from the API reference:

  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "created": 1699896916,
  "model": "gpt-3.5-turbo-0613",
  "choices": [
      "index": 0,
      "message": {
        "role": "assistant",
        "content": null,
        "tool_calls": [
            "id": "call_abc123",
            "type": "function",
            "function": {
              "name": "get_current_weather",
              "arguments": "{\n\"location\": \"Boston, MA\"\n}"
      "logprobs": null,
      "finish_reason": "tool_calls"
  "usage": {
    "prompt_tokens": 82,
    "completion_tokens": 17,
    "total_tokens": 99

This example from the OpenAI Cookbook should help you get to speed with function calling.


Thanks @sps - I did read that doc too, which also makes reference to a ‘hypothetical’ weather function, but nowhere in the documentation do I see a call to a weather API actually specified. Maybe I’m misunderstanding how this works, but presumably it also needs a (python in my case) function that defines get_current_weather as an API call to weatherapi.com or similar?

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Yes the json schema has to be of a function that you can call, once you receive the API response.

Once you have the response, you can validate and form the function call.

def my_function():
    print("Hello, World!")

function_name = "my_function"
f = globals()[function_name]
f()  # This will call my_function

In this example, globals() is used to access the global namespace where my_function is defined. If you’re dealing with a class or module, you would use getattr instead.

In case you need to call a function with arguments, you can simply pass them when calling the function:

def greet(name):
    print(f"Hello, {name}!")

function_name = "greet"
f = globals()[function_name]
f("Alice")  # This will call greet("Alice")

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