function calling

Enables Gemini to invoke developer-defined functions with structured JSON arguments. Define tools, detect function call requests, execute them, and return results.

Syntax

gemini-api

{ tools: [{ functionDeclarations: [{ name, description, parameters }] }] }

Example

gemini-api

const model = genAI.getGenerativeModel({
  model: "gemini-1.5-pro",
  tools: [{
    functionDeclarations: [{
      name: "get_weather",
      description: "Get the weather for a city. Call when user asks about weather.",
      parameters: {
        type: FunctionDeclarationSchemaType.OBJECT,
        properties: {
          city: { type: FunctionDeclarationSchemaType.STRING },
        },
        required: ["city"],
      },
    }],
  }],
});

const response = await model.generateContent("What's the weather in Tokyo?");
const call = response.response.candidates?.[0]?.content.parts[0].functionCall;
console.log(call?.name, call?.args); // "get_weather", { city: "Tokyo" }