Discovery Engine Search Tool

Gemini & Vertex AI Only

This tool leverages Google Cloud's Discovery Engine APIs and is designed for Gemini models running via Vertex AI.

The DiscoveryEngineSearchTool (often used interchangeably with VertexAiSearchTool) provides access to Google Cloud's Discovery Engine to perform semantic searches over indexed PDFs, HTML, and unstructured text.

Usage

Initialize the tool using either a datastore or an engine resource ID:

• Datastore: projects/{project}/locations/{location}/collections/default_collection/dataStores/{datastore_id}
• Engine: projects/{project}/locations/{location}/collections/default_collection/engines/{engine_id}

using GoogleAdk.Core.Agents;
using GoogleAdk.Core.Tools;

var datastoreId = "projects/my-project/locations/global/collections/default_collection/dataStores/hr-docs";

var hrAgent = new LlmAgent(new LlmAgentConfig
{
    Name = "hr_assistant",
    Model = "gemini-2.5-flash",
    Instruction = "You are an HR assistant. Find policies in the HR datastore.",
    Tools = [new DiscoveryEngineSearchTool(datastore: datastoreId)]
});

Vs. RAG Retrieval Tool

Use DiscoveryEngineSearchTool when you want the agent to explicitly decide when and what to search via a standard function call. Use VertexAiRagRetrievalTool to integrate the retrieval directly into the backend generation step.