Gemini 3 Pro

[
  {
    "type": "function",
    "function": {
      "name": "get_current_weather",
      "description": "Get the current weather in a given location",
      "parameters": {
        "type": "object",
        "properties": {
          "location": {
            "type": "string",
            "description": "The city and state, e.g. San Francisco, CA"
          },
          "unit": {
            "type": "string",
            "enum": ["celsius", "fahrenheit"]
          }
        },
        "required": ["location"]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "get_stock_price",
      "description": "Get the current stock price for a given symbol",
      "parameters": {
        "type": "object",
        "properties": {
          "symbol": {
            "type": "string",
            "description": "The stock symbol, e.g. AAPL"
          }
        },
        "required": ["symbol"]
      }
    }
  }
]

​

Function Declaration Requirements

• name (string, required): The unique name of the function (e.g., get_weather_forecast, send_email). Use descriptive names without spaces or special characters (use underscores or camelCase).
• description (string, optional but recommended): A clear and detailed description of what the function does and its purpose. This is crucial for the model to understand when to use the function. Be specific and provide examples when necessary (e.g., “Find movie theaters by location, with an option to also find movies currently showing at those theaters.”).
• parameters (object, required): Defines the input parameters expected by the function. Contains:
  • type (string): Specifies the overall data type, must be "object".
  • properties (object): Lists individual parameters, each with:
    • type (string): The parameter’s data type, such as string, integer, boolean, array.
    • description (string): Description of the parameter’s purpose and format. Provide examples and constraints (e.g., “City and state, e.g. ‘San Francisco, CA’ or a postal code like ‘95616’.”).
    • enum (array, optional): If parameter values come from a fixed set, use enum to list allowed values rather than just describing them in the description. This helps improve accuracy (e.g., "enum": ["daylight", "cool", "warm"]).
  • required (array): An array of strings listing the parameter names required for the function to run.

• string: For text values
• number: For floating-point numbers
• integer: For whole numbers
• boolean: For true/false values
• object: For structured data with key-value pairs
• array: For lists of items
• null: To allow null values, add "null" to the type array (e.g., {"type": ["string", "null"]})

​

Type-Specific Properties

• properties: Object mapping property names to their schema definitions
• required: Array of required property names
• additionalProperties: Controls whether properties not in properties are allowed

• enum: List of specific possible string values for classification
• format: Specifies string syntax (e.g., date-time, date, time)

• enum: List of specific possible numeric values
• minimum: Inclusive minimum value
• maximum: Inclusive maximum value

• items: Schema definition for all array elements
• prefixItems: List of schemas for the first N items (tuple-like structures)
• minItems: Minimum number of items in the array
• maxItems: Maximum number of items in the array

• Clear descriptions: Use the description field in the schema to clearly explain what each property means
• Strong typing: Use specific types (integer, string, enum) whenever possible
• Prompt engineering: Clearly state in your prompt what you want the model to extract or structure
• Validation: While structured output ensures JSON is syntactically correct, always validate the semantic correctness of values in your application code