flat-fuchsia•4mo ago

Format to return mcp server response to vapi tool call.

Is there a specific format that we need to follow to return a response from vapi tool call to an mcp server ?

4 Replies

Yes, there is a specific format you must follow when returning a response from your MCP server to a Vapi tool call.
Return a JSON object like this:

{
  "results": [
    {
      "toolCallId": "YOUR_TOOL_CALL_ID",
      "result": "YOUR_RESULT"
    }
  ]
}

{
  "results": [
    {
      "toolCallId": "YOUR_TOOL_CALL_ID",
      "result": "YOUR_RESULT"
    }
  ]
}

Replace YOUR_TOOL_CALL_ID with the ID from the incoming request, and YOUR_RESULT with your tool's output.
See official docs for details. Source: - Vapi Custom Tools Documentation

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

flat-fuchsiaOP•4mo ago

@Duckie I do not see the toold id in the mcp server query

Vapi Support Bot•4mo ago

To return a response from your MCP server to a Vapi tool call, use this JSON format:

{
  "results": [
    {
      "toolCallId": "YOUR_TOOL_CALL_ID",
      "result": "YOUR_RESULT"
    }
  ]
}

{
  "results": [
    {
      "toolCallId": "YOUR_TOOL_CALL_ID",
      "result": "YOUR_RESULT"
    }
  ]
}

Replace YOUR_TOOL_CALL_ID with the ID from the incoming request (look for it in the tool call payload), and set YOUR_RESULT to your tool's output. This format is required for Vapi to process your tool's response correctly.
See official docs for details. Source: - Vapi Custom Tools Documentation

Sahil•4mo ago

Yes, when Vapi AI sends a tool-call to your MCP server, you must return a valid JSON response in the format {"result": "your message"} or {"result": {"message": "your message", "data": {...}}} to ensure proper integration and response handling.

Format to return mcp server response to vapi tool call.

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