Automated voice appointment booking with Vapi AI and Google Calendar
## 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
1. Open the **Webhook** node and copy the **Production URL**.
2. In **Vapi** → **Assistant** → **Messaging**, set **Server URL** = that Production URL.
3. 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
1. Open **2. Get Calendar Events (EDIT ME)** → Credentials: select/create Google Calendar OAuth.
Then choose the calendar to check availability.
2. 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.
