Vapi Voice Agent Tool Calls + Call Logging with Google Sheets & Gmail

Turn Vapi voice tool calls into real-time Google Calendar + Sheets actions—then log every call with keyword alerts

This n8n workflow acts as a single webhook backend for Vapi voice agents. It handles mid-call tool calls using Google Calendar and Google Sheets, then logs end-of-call details to a Google Sheets “Calls” tab and sends Gmail follow-up alerts when configured keywords are detected.

What this workflow does

• Receives POST requests from Vapi through one webhook for both tool call events and end-of-call reports.
• Normalizes the payload to extract key fields including event type, tool call details, caller number, call ID, transcript, summary, and call metadata.
• Routes mid-call tool requests by function name to:
  • Check Google Calendar availability.
  • Look up customer information in Google Sheets.
  • Append a request to Google Sheets.
  • Return a safe response for unknown functions.
• Returns Vapi tool results immediately in the required format: { results: [{ toolCallId, result }] }.
• On end-of-call, scans transcript and summary for configured FollowUpKeywords, sets follow-up flags, then:
  • Appends the call record to the Google Sheets “Calls” tab.
  • Sends a Gmail alert email only if the call is flagged for follow-up.
  • Acknowledges receipt back to Vapi.

Use cases

• Automated appointment scheduling during live voice calls with calendar availability checks.
• Enriching conversations by looking up customers in Google Sheets and recording new requests.
• Operations and sales follow-up: alert the right team via Gmail when keywords appear in transcripts/summaries.

Technical details

• Webhook backend for Vapi events (tool calls + end-of-call reports).
• Integrations: Google Calendar, Google Sheets, Gmail.
• n8n node types used: if, set, code, gmail, switch, webhook.
• Configurable values include CalendarId, AlertEmail, SlotLengthMinutes, TransferMessage, and FollowUpKeywords.