If you're getting responses like:

• "I don’t understand, please rephrase the question"

• or no answer at all

Then here are the most common issues and how to fix them:

Step-by-Step Checklist

1. Data Store Might Not Be Indexed Correctly

• Make sure your website allows crawling (robots.txt should not block bots).

• Add a sitemap if your site has dynamic pages.

• Ensure your content is text-based and not loaded only via JavaScript.

• Check that the Data Store status is “Ready” (not "Pending" or "Failed").

2. Document Retriever Tool Is Missing

• In the Agent Builder console, go to the Tools tab.

• Make sure the Document Retriever tool is added.
  Without this, your agent won’t be able to search the connected Data Store.

3. System Prompt Missing Tool Instructions

Your system message should explicitly tell the agent to use the tool. For example:

Please use the document retriever tool to answer questions when helpful.

4. Intent Confidence Is Too High

• In the Agent Settings, reduce the Intent Confidence Threshold to around 0.3.

• A higher value may prevent the agent from attempting to answer reasonable queries.

5. Use Gemini REST API for Full Control

If you're still not getting the desired results, you can bypass Agent Builder and use the Gemini REST API directly for full flexibility.

Here’s a complete working guide using Java Spring Boot and Gemini:

Spring Boot + Gemini Vertex AI REST API + GCS + Config Guide

Additional Debugging Tips

• Use tools like curl or Postman to verify the Data Store endpoint independently.

• Enable Agent Monitoring Logs to inspect how your queries are handled.