Implementation:Openai Openai python Function Tool Param

Knowledge Sources	Openai_Openai_python OpenAI API Reference
Domains	API_Types, Responses_API
Last Updated	2026-02-15 00:00 GMT

Overview

Concrete parameter type for defining a custom function tool that the model can choose to call, provided by the openai-python SDK.

Description

FunctionToolParam is a TypedDict used to define a function in your own code that the model can choose to call via the Responses API. It includes the function name, a JSON Schema describing the parameters, an optional description for the model to decide when to invoke it, and a strict flag for parameter validation. The type field is always "function". This type is auto-generated from the OpenAI OpenAPI specification by Stainless.

Usage

Import FunctionToolParam when constructing tool definitions for a Responses API request where you want to expose custom functions the model can call.

Code Reference

Source Location

• Repository: openai-python
• File: src/openai/types/responses/function_tool_param.py

Signature

class FunctionToolParam(TypedDict, total=False):
    """Defines a function in your own code the model can choose to call."""

    name: Required[str]
    parameters: Required[Optional[Dict[str, object]]]
    strict: Required[Optional[bool]]
    type: Required[Literal["function"]]
    description: Optional[str]

Import

from openai.types.responses import FunctionToolParam

I/O Contract

Fields

Name	Type	Required	Description
name	str	Yes	The name of the function to call.
parameters	Optional[Dict[str, object]]	Yes	A JSON schema object describing the parameters of the function.
strict	Optional[bool]	Yes	Whether to enforce strict parameter validation. Default true.
type	Literal["function"]	Yes	The type of the function tool. Always "function".
description	Optional[str]	No	A description of the function, used by the model to determine whether to call it.

Usage Examples

from openai.types.responses import FunctionToolParam

tool: FunctionToolParam = {
    "name": "get_weather",
    "type": "function",
    "parameters": {
        "type": "object",
        "properties": {
            "location": {"type": "string"},
        },
        "required": ["location"],
    },
    "strict": True,
    "description": "Get the current weather for a location.",
}

response = client.responses.create(
    model="gpt-4o",
    input="What is the weather in London?",
    tools=[tool],
)

Related Pages

• Environment:Openai_Openai_python_Python_3_9_Plus