Trouble Integrating AI Agent with Ultravox + n8n — Stuck on Tool ID & Timeout

Hey there — I’ve been working on this for a couple of days and haven’t been able to resolve the issue.

I’m trying to use an AI agent (via Ultravox) to fetch calendar data through a simple n8n webhook. When Ultravox hits the webhook, I respond using the “Respond to Webhook” node, but I keep getting this error on the Ultravox side:

Endpoint {my webhook url} took more than 2.5s to respond.

To work around that, I created a split flow: I send a temporary response (status: “processing”) while the agent does its thing in the background. However, for the final response to be sent back to Ultravox, I believe I need a toolCallId. The problem is — I’m not seeing that ID in any of the webhook payloads, so I can’t complete the tool result.

Would love to get some guidance from someone to walk through this. Any help would be massively appreciated!


Information on your n8n setup

  • n8n version: 1.90.2
  • Running n8n via (Docker, npm, n8n cloud, desktop app): Docker
  • Operating system: M1 Mac