Grounding API

In generative AI, grounding is the ability to connect model output to verifiable sources of information. If you provide models with access to specific data sources, then grounding tethers their output to these data and reduces the chances of inventing content.

With Vertex AI, you can ground model outputs in the following ways:

  • Ground with Google Search - ground a model with publicly-available web data.
  • Ground with Google Maps - ground a model with geospatial data from Google Maps.
  • Ground to your data - ground a model with your data from Vertex AI Search as a data store.

For more information about grounding, see Grounding overview.

Supported models

Parameter list

See examples for implementation details.

googleSearch

Ground the response with publicly-available web data from Google Search.

googleMaps

Ground the response with publicly-available geospatial data from Google Maps.

The API input includes the following parameter:

Input parameter

enable_widget

Required: boolean

Flag that can be set to true or false. A value of true returns a token using the API response that you can use with the Google Maps context widget user interface.

The API response structure includes the following parameter:

Response parameter

grounding_metadata

Required: Object

The primary field that contains grounding information.
  • grounding_support: A sub-field indicating the level of grounding support.
  • grounding_chunks.maps: A sub-field containing the places sources used to generate the grounded response.
    • place_answer_sources.review_snippets: A sub-field within grounding_chunks.maps that appears when a place answer is used to answer a query. Place answers provide deeper contextual information about a specific place using data, such as user reviews. The place answer is backed by a list of sources like user reviews.

Attributes

A place or user review source has the following attributes:

Attributes

title

Required: Object

The title of the source.

uri

Required: string

A URI linking to the source.

place_id

Required: string

A unique identifier for the place.

review_id

Required: string

A unique identifier for review.

retrieval

Ground the response with private data from Vertex AI Search as a data store. Defines a retrieval tool that the model can call to access external knowledge.

Parameters

vertexAiSearch

Required: VertexAISearch

Ground with Vertex AI Search data sources.

VertexAISearch

Parameters

datastore

Required: string

Fully-qualified data store resource ID from Vertex AI Search, in the following format: projects/{project}/locations/{location}/collections/default_collection/dataStores/{datastore}

Examples

This section provides examples for grounding a response on public web data using Google Search and grounding a response on private data using Vertex AI Search.

Ground response on public web data using Google Search

Ground the response with Google Search public data. Include the google_search_retrieval tool in the request. No additional parameters are required.

Python

Install

pip install --upgrade google-genai

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

from google import genai
from google.genai.types import (
    GenerateContentConfig,
    GoogleSearch,
    HttpOptions,
    Tool,
)

client = genai.Client(http_options=HttpOptions(api_version="v1"))

response = client.models.generate_content(
    model="gemini-2.5-flash",
    contents="When is the next total solar eclipse in the United States?",
    config=GenerateContentConfig(
        tools=[
            # Use Google Search Tool
            Tool(google_search=GoogleSearch())
        ],
    ),
)

print(response.text)
# Example response:
# 'The next total solar eclipse in the United States will occur on ...'

Go

Learn how to install or update the Go.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

import (
	"context"
	"fmt"
	"io"

	genai "google.golang.org/genai"
)

// generateWithGoogleSearch shows how to generate text using Google Search.
func generateWithGoogleSearch(w io.Writer) error {
	ctx := context.Background()

	client, err := genai.NewClient(ctx, &genai.ClientConfig{
		HTTPOptions: genai.HTTPOptions{APIVersion: "v1"},
	})
	if err != nil {
		return fmt.Errorf("failed to create genai client: %w", err)
	}

	modelName := "gemini-2.5-flash"
	contents := []*genai.Content{
		{Parts: []*genai.Part{
			{Text: "When is the next total solar eclipse in the United States?"},
		},
			Role: "user"},
	}
	config := &genai.GenerateContentConfig{
		Tools: []*genai.Tool{
			{GoogleSearch: &genai.GoogleSearch{}},
		},
	}

	resp, err := client.Models.GenerateContent(ctx, modelName, contents, config)
	if err != nil {
		return fmt.Errorf("failed to generate content: %w", err)
	}

	respText := resp.Text()

	fmt.Fprintln(w, respText)

	// Example response:
	// The next total solar eclipse in the United States will occur on March 30, 2033, but it will only ...

	return nil
}

Java

Learn how to install or update the Java.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 


import com.google.genai.Client;
import com.google.genai.types.GenerateContentConfig;
import com.google.genai.types.GenerateContentResponse;
import com.google.genai.types.GoogleSearch;
import com.google.genai.types.HttpOptions;
import com.google.genai.types.Tool;

public class ToolsGoogleSearchWithText {

  public static void main(String[] args) {
    // TODO(developer): Replace these variables before running the sample.
    String modelId = "gemini-2.5-flash";
    generateContent(modelId);
  }

  // Generates text with Google Search tool
  public static String generateContent(String modelId) {
    // Initialize client that will be used to send requests. This client only needs to be created
    // once, and can be reused for multiple requests.
    try (Client client =
        Client.builder()
            .location("global")
            .vertexAI(true)
            .httpOptions(HttpOptions.builder().apiVersion("v1").build())
            .build()) {

      // Create a GenerateContentConfig and set Google Search tool
      GenerateContentConfig contentConfig =
          GenerateContentConfig.builder()
              .tools(Tool.builder().googleSearch(GoogleSearch.builder().build()).build())
              .build();

      GenerateContentResponse response =
          client.models.generateContent(
              modelId, "When is the next total solar eclipse in the United States?", contentConfig);

      System.out.print(response.text());
      // Example response:
      // The next total solar eclipse in the United States will occur on...
      return response.text();
    }
  }
}

Ground response on private data using Vertex AI Search

Ground the response with data from a Vertex AI Search data store. For more information, see Vertex AI Search.

Before you ground a response with private data, create a data store and a search app.

WARNING: For the time being, this "grounding" interface does not support Vertex AI Search "chunk mode".

Gen AI SDK for Python

from google import genai
from google.genai.types import (
    GenerateContentConfig,
    HttpOptions,
    Retrieval,
    Tool,
    VertexAISearch,
)

client = genai.Client(http_options=HttpOptions(api_version="v1"))

# Load Data Store ID from Vertex AI Search
# datastore = "projects/111111111111/locations/global/collections/default_collection/dataStores/data-store-id"

response = client.models.generate_content(
    model="gemini-2.5-flash",
    contents="How do I make an appointment to renew my driver's license?",
    config=GenerateContentConfig(
        tools=[
            # Use Vertex AI Search Tool
            Tool(
                retrieval=Retrieval(
                    vertex_ai_search=VertexAISearch(
                        datastore=datastore,
                    )
                )
            )
        ],
    ),
)

print(response.text)
# Example response:
# 'The process for making an appointment to renew your driver's license varies depending on your location. To provide you with the most accurate instructions...'

What's next

For detailed documentation, see the following: