ToolDefinition class

Defines a tool that the LLM can invoke.

A tool definition includes:

• A unique name that the model uses to reference the tool.
• A description explaining what the tool does (helps the model decide when to use it).
• A list of parameters defining the expected input schema.
• A handler function that executes the tool logic.

Example:

final weatherTool = ToolDefinition(
  name: 'get_weather',
  description: 'Get the current weather for a location',
  parameters: [
    ToolParam.string('location', description: 'City name', required: true),
    ToolParam.enumType('unit', values: ['celsius', 'fahrenheit']),
  ],
  handler: (params) async {
    final location = params.getRequiredString('location');
    final unit = params.getString('unit') ?? 'celsius';
    // Fetch weather...
    return 'Weather in $location: 22°$unit';
  },
);