I have the following use case: 1. Caller wants to reschedule a booking 2. VAPI uses tool that enables n8n to collect information about the inquired booking and return "success" if tool found the appointment. 3. Using an API call I update the resumeURL for assistant.server.url via PATCH

https://api.vapi.ai/assistant/:id

4. I then request VAPI assistant to confirm its the correct booking by asking the caller to confirm their name. 5. Once confirmed, I want VAPI to resume my n8n workflow by calling a tool that will continue to update/cancel a booking. I intentionally leave the server URL field of the tool empty as documentation mentions the priority will default up the ladder to the assistant server url. This is where my issue arises, it does not default to the assistant server url (i can see it was set successfuly via the API call response) in turn erroring out my workflow and agent.

Thank you for the detailed explanation. To help diagnose why the tool is not defaulting to the assistant's server URL, could you clarify: After updating the assistant.server.url via PATCH, are you starting a new call/session, or is the tool being invoked within the same ongoing session? This will help determine if the updated URL is being picked up as expected according to the documented priority rules ([see docs](https://docs.vapi.ai/server-url/setting-server-urls)). Source: - [Setting Server URLs | Vapi Documentation](https://docs.vapi.ai/server-url/setting-server-urls)

it is being invoked within the same ongoing session

Based on the documentation, changes to

assistant.server.url

via PATCH may not take effect for tools invoked within an ongoing session. To ensure the updated URL is used, try ending the current call/session and starting a new one after updating the assistant's server URL. Example:

bash
# Update assistant.server.url
PATCH https://api.vapi.ai/assistant/:id

# Start a new call/session to pick up the new URL

For more details, see the [server URL priority documentation](https://docs.vapi.ai/server-url/setting-server-urls). Source: - [Setting Server URLs | Vapi Documentation](https://docs.vapi.ai/server-url/setting-server-urls)

what about changes done to tool.server.url, would tos get updated realtime if I have the API request update the server URL before having VAPI call the tool? @Vapi Support Bot

The documentation does not explicitly confirm whether updating

tool.server.url

via API takes effect in real-time during an ongoing session. To ensure the updated URL is used, the safest approach is to update the tool's server URL before the session starts or to restart the session after making the change. Example API call to update a tool's server URL:

bash
PATCH https://api.vapi.ai/tool/<tool-id>
Content-Type: application/json
Authorization: Bearer <YOUR_API_KEY>

{
  "server": {
    "url": "https://your-new-endpoint.com/webhook"
  }
}

For best results, apply the update before invoking the tool in a new session. See: [Vapi server URL documentation](https://docs.vapi.ai/server-url/setting-server-urls) Source: - [Setting Server URLs | Vapi Documentation](https://docs.vapi.ai/server-url/setting-server-urls)

How can I accomplish that use case then, I want to be able to pass in a resumeURL from n8n to VAPI so that it can execute tool at serverURL i provide at run-time @User @User

Please note that once the call starts, assistant config and tool config are not updatable. Any updates made will apply once the active call ends. With that being said, I'm curious as to how your workflow is connected. If you are getting a URL for the tool from n8n, then having the assistant send a webhook to the tool URL, which is also in n8n, why not just have one tool call in VAPI and let n8n do all the backend work?