I’m reaching out regarding an issue I’m facing with the Knowledge Base integration for my assistant in VAPI. Problem Summary I’ve added a knowledge base for my query tool and attached it to my assistant. I uploaded a FAQ file as CSV, PDF, Docx, txt format. The assistant is not retrieving answers from the knowledge base. Instead, I only get a generic 'Success' response. This issue has been blocking me despite following the documentation, and I’d appreciate your help in diagnosing what’s going wrong. Thanks in advance for your support. https://cdn.discordapp.com/attachments/1418516815964798999/1418516816191295488/Screenshot_from_2025-09-19_14-09-20.png?ex=68ce683b&is=68cd16bb&hm=4992d1acfd8eea6ad7fb575ab2f0d1607d0b592203f55c1280f41db27e30e139&

Suggestion: Make sure your assistant's system prompt explicitly instructs it to use your query tool by its exact function name (e.g.,

query_tool

). For example, add this to your system prompt:

json
{
  "role": "system",
  "content": "When users ask about HVAC software, use the 'query_tool' to search the knowledge base for answers. Always call the query_tool before responding."
}

Update and republish your assistant after making this change. [See documentation for details](https://docs.vapi.ai/knowledge-base/using-query-tool). Source: - [Using the Query Tool for Knowledge Bases](https://docs.vapi.ai/knowledge-base/using-query-tool)

The functionality works when making outbound calls through the Assistant (data is correctly read from the file). However, it does not work in Vapi Chat or within the Vapi widget.

If you have any

messages

for your query tool, we suggest removing them as sometimes they can prevent successful reads from knowledge bases. As for chat/widget functionality with KBs, you will have to run some tests as sometimes the results can be inconsistent. Let us know how it goes for you