Function / Tool-Calling Schema Generator

Build a function definition once and get the OpenAI tool-calling or Anthropic tool-use JSON schema for it, without hand-writing nested JSON Schema.

Function name

Description

Parameters

required

{
  "type": "function",
  "function": {
    "name": "get_weather",
    "description": "Get the current weather for a given location.",
    "parameters": {
      "type": "object",
      "properties": {
        "location": {
          "type": "string",
          "description": "City and state, e.g. San Francisco, CA"
        },
        "unit": {
          "type": "string",
          "enum": [
            "celsius",
            "fahrenheit"
          ],
          "description": "Temperature unit"
        }
      },
      "required": [
        "location"
      ]
    }
  }
}

Both providers use JSON Schema for parameters — the wrapper differs (OpenAI nests under function.parameters, Anthropic uses input_schema at the top level). 100% client-side.

About the Tool-Calling Schema Generator

Both OpenAI's function/tool calling and Anthropic's tool use expect a JSON Schema description of each parameter, wrapped slightly differently per provider. Hand-writing that nested JSON — types, enums, required lists — is repetitive and error-prone. This tool lets you define parameters through a form and generates valid, correctly-wrapped JSON for either provider.

Key Features

Supports string, number, boolean, enum, array, and object parameter types.
Outputs the OpenAI tools array format or Anthropic's input_schema format.
Pairs with the JSON to Zod/Pydantic generator for validating the arguments a model returns.

Function / Tool-Calling Schema Generator

About the Tool-Calling Schema Generator

Key Features

Tools Related to Function/Tool Schema Generator

JSON Schema Mock Data

JSON → Zod/Pydantic

Tool Schema → OpenAPI

Structured Output Validator