What this template does Connect a Vapi AI voice agent to Google Calendar to capture contact details and auto-book appointments. The agent asks for name, address, service type, and a preferred time. The workflow checks availability and either proposes times or books the slot—no code needed. How it works (node map) Webhook: Production URL = VAPI Server URL — receives tool calls from Vapi and returns results. 1. CONFIGURATION (EDIT ME) — your timezone, work hours, meeting length, buffers, and cadence. Route by Tool Name — routes Vapi tool calls: checkAvailability → calendar lookup path bookAppointment → create event path 2. Get Calendar Events (EDIT ME) — reads events for the requested day. Calculate Potential Slots / Filter for Available Slots — builds conflict-free options with buffers. Respond with Available Times — returns formatted slots to Vapi. 3. Book Appointment in Calendar (EDIT ME) — creates the calendar event with details. Booking Confirmation — returns success back to Vapi. Sticky notes in the canvas show exactly what to edit (required by n8n). No API keys are hardcoded; Google uses OAuth credentials. Requirements n8n (Cloud or self-hosted) Google account with Calendar (OAuth credential in n8n) Vapi account + one Assistant Setup (5 minutes) A) Vapi → n8n connection Open the Webhook node and copy the Production URL . In Vapi → Assistant → Messaging , set Server URL = that Production URL. In Server Messages , enable only toolCalls . B) Vapi tools (names must match exactly) Create two Custom Tools in Vapi and attach them to the assistant: Tool 1: checkAvailability Arguments initialSearchDateTime (string, ISO-8601 with timezone offset, e.g. 2025-09-09T09:00:00-05:00 ) Tool 2: bookAppointment Arguments startDateTime (string, ISO-8601 with tz) endDateTime (string, ISO-8601 with tz) clientName (string) propertyAddress (string) serviceType (string) The Switch node routes based on message.toolCalls[0].function.name . If the names differ, nothing will run. C) Configure availability Open 1. CONFIGURATION (EDIT ME) and set: timeZone (e.g. America/New_York ) workdayStartHour / workdayEndHour (24h integers) meetingDurationMinutes (e.g. 30 or 60 ) bufferBeforeMinutes / bufferAfterMinutes (e.g. 15 ) bookingCadenceMinutes (e.g. 30 ) D) Connect Google Calendar Open 2. Get Calendar Events (EDIT ME) → Credentials: select/create Google Calendar OAuth. Then choose the calendar to check availability. Open 3. Book Appointment in Calendar (EDIT ME) → use the same credential and same calendar to book. E) Activate & test Toggle the workflow Active . Call your Vapi number (or start a session) and book a test slot. Verify the event appears with description fields (client, address, service type, call id). Customising Change summary/description format in 3. Book Appointment . Add SMS/Email confirmations, CRM sync, rescheduling, or analytics as follow-ups (see sticky note “I’m a note”). Troubleshooting No response back to Vapi → confirm Vapi is set to send toolCalls only and the Server URL matches the Production URL. Switch doesn’t route → tool names must be exactly checkAvailability and bookAppointment. No times returned → ensure timezone + work hours + cadence generate at least one future slot; confirm Google credential and calendar selection. Event not created → use the same Google credential & calendar in both nodes; check OAuth scopes/consent. Security & privacy Google uses OAuth; credentials live in n8n. No API keys hardcoded. Webhook receives only the fields needed to check times or book.