Combine built-in tools and function calling

Gemini allows the combination of built-in tools, such as google_search, and function calling (also known as custom tools) in a single interaction by preserving and exposing the context history of tool calls. Built-in and custom tool combinations allow for complex, agentic workflows where, for example, the model can ground itself in real-time web data before calling your specific business logic.

Here's an example that enables built-in and custom tool combinations with google_search and a custom function getWeather:

Python

# This will only work for SDK newer than 2.0.0
from google import genai

client = genai.Client()

getWeather = {
    "type": "function",
    "name": "getWeather",
    "description": "Gets the weather for a requested city.",
    "parameters": {
        "type": "object",
        "properties": {
            "city": {
                "type": "string",
                "description": "The city and state, e.g. Utqiaġvik, Alaska",
            },
        },
        "required": ["city"],
    },
}

# The Interactions API manages context automatically across tool calls.
# The model will first use Google Search, then call getWeather.
interaction = client.interactions.create(
    model="gemini-3.7-flash",
    input="What is the northernmost city in the United States? What's the weather like there today?",
    tools=[
        {"type": "google_search"},
        getWeather,
    ],
)

# Process steps: the interaction contains search results and a function call
for step in interaction.steps:
    if step.type == "function_call":
        print(f"Function call: {step.name} with args: {step.arguments}")
        # In a real application, you would execute the function here
        # and provide the result back to the model.

JavaScript

// This will only work for SDK newer than 2.0.0
import { GoogleGenAI } from '@google/genai';

const client = new GoogleGenAI({});

const getWeather = {
    type: "function",
    name: "getWeather",
    description: "Get the weather in a given location",
    parameters: {
        type: "object",
        properties: {
            location: {
                type: "string",
                description: "The city and state, e.g. San Francisco, CA"
            }
        },
        required: ["location"]
    }
};

// The Interactions API manages context automatically across tool calls.
// The model will first use Google Search, then call getWeather.
const interaction = await client.interactions.create({
    model: "gemini-3.7-flash",
    input: "What is the northernmost city in the United States? What's the weather like there today?",
    tools: [
        { type: "google_search" },
        getWeather,
    ],
});

// Process steps: the interaction contains search results and a function call
for (const step of interaction.steps) {
    if (step.type === "function_call") {
        console.log(`Function call: ${step.name} with args: ${JSON.stringify(step.arguments)}`);
        // In a real application, you would execute the function here
        // and provide the result back to the model.
    }
}

REST

# Specifies the API revision to avoid breaking changes when they become default
curl -X POST "https://generativelanguage.googleapis.com/v1beta/interactions" \
-H "Content-Type: application/json" \
-H "x-goog-api-key: $GEMINI_API_KEY" \
-d '{
  "model": "gemini-3.7-flash",
  "input": "What is the northernmost city in the United States? What'\''s the weather like there today?",
  "tools": [
    { "type": "google_search" },
    {
      "type": "function",
      "name": "getWeather",
      "description": "Get the weather in a given location",
      "parameters": {
          "type": "object",
          "properties": {
              "location": {
                  "type": "string",
                  "description": "The city and state, e.g. San Francisco, CA"
              }
          },
          "required": ["location"]
      }
    }
  ]
}'

How it works

Gemini 3 models use tool context circulation to enable built-in and custom tool combinations. Tool context circulation makes it possible to preserve and expose the context of built-in tools and share it with custom tools in the same interaction.

Enable tool combination

  • Include the