OpenAI Function Calling Schema Builder

Build OpenAI function calling schemas with visual parameter configuration, validation rules, nested objects/arrays, schema testing, and automatic name sanitization. Export as single function or array format with strict mode validation.

OpenAI Function Calling Schema Format:

  • Each tool has type: "function" at the top level
  • Function properties (name, description, parameters) are at the same level as type
  • Parameters use JSON Schema format with type definitions
  • Use additionalProperties: false for strict validation
  • Mark required parameters to ensure they're included in calls
  • Supports nested objects and arrays with complex structures

Build Your Functions

No functions added yet. Click "Add Function" to start.

Example: Create a "get_weather" function with location parameter

{
  "type": "function",
  "name": "get_weather",
  "description": "Get current temperature for a given location",
  "parameters": {
    "type": "object",
    "properties": {
      "location": {
        "type": "string",
        "description": "City and country e.g. Bogotá, Colombia"
      }
    },
    "required": ["location"],
    "additionalProperties": false
  }
}

Generated Schema

Tips:

  • Edit the JSON schema directly and click the save icon to update the visual builder
  • The type: "function" field is automatically included for OpenAI compatibility
  • Use the format field for strings to add semantic validation
  • Parameters marked as required will be mandatory in function calls
  • Enable "Strict Mode" to add strict: true, additionalProperties: false, and make all properties required (including nested objects and arrays)
  • Use the test section below to validate your function calls

Test Your Functions

Test your function schema with a sample call. The test data should be in the format:

⚠️ No functions added yet. Click "Add Function" to start building your schema.