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Feature Highlights
n8n acts as the agent's toolbox through a single connection
- An MCP server workflow defines the tools; each tool's logic lives in its own sub-workflow
- Tools can be updated or added without reconfiguring the voice assistant
- The model keeps the conversation context, so one call can use several tools in a row
- Details like name and email are only asked for when a tool actually needs them
Stack
- Vapi: Voice assistant that runs the call and calls tools mid-conversation.
- n8n MCP Server: Exposes the agent's tools through one MCP endpoint, with sub-workflows for the logic.
- GPT-4o: Reasons over the conversation and decides which tool to call.
- Google Calendar: Availability checks and appointment creation.
- Twilio: Phone number and call routing into the voice agent.
- Call Transfer: Native transfer tool for handing callers to a person.
Use Cases
- Service businesses that miss calls after hours or while staff are busy
- Booking appointments straight into a calendar without a receptionist
- Routing callers who need a person to the right team member
How It Works
- A caller rings the business number, routed through Twilio to the Vapi agent.
- The agent talks with the caller and decides which tool it needs.
- It calls the n8n MCP server to check the calendar and book the slot, or offer alternatives.
- If the caller wants a person, or the agent can't understand them, it transfers the call.
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