FileSearch tool not working with generateContent - missing tool_type field

[yarivMobitti]

What I'm trying to do:

I'm trying to use the File Search feature with the Gemini API via the Java SDK. Specifically, I want to:

1. Create a File Search Store
2. Upload documents to it
3. Query the store using generateContent with a FileSearch tool

The store creation and file upload work perfectly, but querying fails when using the FileSearch tool.

Code I've tried:

import com.google.genai.Client;
import com.google.genai.types.*;

public class FileSearchExample {
public static void main(String[] args) throws Exception {
String apiKey = "YOUR_API_KEY";
Client client = Client.builder().apiKey(apiKey).build();

      // This works fine - store and file upload
      FileSearchStore store = client.fileSearchStores.create(
          CreateFileSearchStoreConfig.builder()
              .displayName("Test Store")
              .build()
      );
      String storeId = store.name().get();

      // Upload and import file (this also works)
      File uploadedFile = client.files.upload(
          new java.io.File("document.pdf"),
          UploadFileConfig.builder().displayName("Test Doc").build()
      );
      client.fileSearchStores.importFile(
          storeId,
          uploadedFile.name().get(),
          ImportFileConfig.builder().build()
      );

      // THIS FAILS - Query with FileSearch tool
      Tool tool = Tool.builder()
          .fileSearch(FileSearch.builder()
              .fileSearchStoreNames(storeId)
              .build())
          .build();

      GenerateContentResponse response = client.models.generateContent(
          "gemini-2.0-flash-exp",
          "What is this document about?",
          GenerateContentConfig.builder()
              .tools(List.of(tool))
              .build()
      );
  }

}

Error message:

Exception in thread "main" com.google.genai.errors.ClientException: 400 . The GenerateContentRequest proto is invalid:
* tools[0].tool_type: required one_of 'tool_type' must have one initialized field
at com.google.genai.errors.ApiException.throwFromResponse(ApiException.java:94)
at com.google.genai.HttpApiResponse.getBody(HttpApiResponse.java:37)
at com.google.genai.Models.processResponseForPrivateGenerateContent(Models.java:4708)
at com.google.genai.Models.privateGenerateContent(Models.java:4762)
at com.google.genai.Models.generateContent(Models.java:6090)
at com.google.genai.Models.generateContent(Models.java:6164)

Expected behavior:

The SDK should properly serialize the FileSearch tool and send it to the API, similar to how the REST API works with this JSON structure:

{
"contents": [{"parts": [{"text": "What is this document about?"}]}],
"tools": [{
"retrieval": {
"fileSearch": {
"fileSearchStoreNames": ["fileSearchStores/abc123"]
}
}
}]
}

Environment:

• SDK Version: com.google.genai:google-genai:1.26.0
• Java Version: 21
• OS: macOS

Additional context:

The REST API documentation shows that File Search should work with the retrieval tool type containing a fileSearch configuration: https://ai.google.dev/api/file-search/file-search-stores

The error message suggests that the Tool object isn't properly setting the tool_type field when using fileSearch(). It seems like the SDK might be missing the proper mapping between the FileSearch builder and the underlying proto field.

[hemasekhar-p]

Thank you for bringing this to our attention, I will recommend you to change the model from Gemini-2.0-flash-exp to gemini-2.5-flash. I will provide the code below for your reference, Please try this change and let us know if it resolves the issue for you.

Solution :
package com.example.repros.dec2025;

import com.example.repros.constants.GenAIConstants;
import com.google.genai.Client;
import com.google.genai.types.*;
import java.io.File;
import java.io.FileWriter;
import java.util.Collections;
import java.util.Optional;

public class FileSearchExample {

public static void verifyFileSearch() throws Exception {
    // 1. Setup Client
    String apiKey = "GOOGLE_API_KEY";
    if (apiKey == null) {
        throw new RuntimeException("GOOGLE_API_KEY environment variable is missing!");
    }
    Client client = Client.builder().apiKey(apiKey).vertexAI(false).build();

    File dummyFile = new File("repro_document.txt");
    try (FileWriter writer = new FileWriter(dummyFile)) {
        writer.write("This is a test document to reproduce issue #685.");
    }

    try {
        // 2. Create Store
        FileSearchStore store = client.fileSearchStores.create(
            CreateFileSearchStoreConfig.builder().displayName("Repro Store").build()
        );
        Optional<String> storeId = store.name();

        // 3. Upload File 
        com.google.genai.types.File uploadedFile = client.files.upload(
            dummyFile,
            UploadFileConfig.builder()
                .displayName("Repro Doc")
                .mimeType("text/plain") // Use text/plain for safety
                .build()
        );

        // 4. Import File
        client.fileSearchStores.importFile(
            storeId.get(),
            uploadedFile.name().get(),
            ImportFileConfig.builder().build()
        );

        // 5. Trigger the Bug (The Broken Tool)
        Tool brokenTool = Tool.builder()
            .fileSearch(FileSearch.builder()
                .fileSearchStoreNames(Collections.singletonList(storeId.get()))
                .build())
            .build();

      
        GenerateContentResponse response=client.models.generateContent(
            "gemini-2.5-flash", 
            "What is this document about?",
            GenerateContentConfig.builder()
                .tools(Collections.singletonList(brokenTool))
                .build()
        );
        System.out.println("response : "+response.toJson());


    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (dummyFile.exists()) {
            dummyFile.delete();
        }
    }
}

}