Vapi MCP Server

Build AI voice assistants and phone agents with Vapi using the Model Context Protocol.

Using Variable Values in Assistant Prompts

The create_call action supports passing dynamic variables through assistantOverrides.variableValues. Use double curly braces in your assistant's prompts: {{variableName}}.

Example Prompt with Variables

Hello {{customerName}}, this is a reminder about your appointment on {{appointmentDate}} at {{appointmentTime}} with {{doctorName}}.

Default Variables

These are automatically available (no need to pass):

• {{now}} - Current date and time (UTC)
• {{date}} - Current date (UTC)
• {{time}} - Current time (UTC)
• {{month}} - Current month (UTC)
• {{day}} - Current day of month (UTC)
• {{year}} - Current year (UTC)
• {{customer.number}} - Customer's phone number

See Vapi documentation for advanced date/time formatting.

Remote MCP Server

Connect to Vapi's hosted MCP server from any MCP client:

Streamable HTTP (Recommended)

• URL: https://mcp.vapi.ai/mcp
• Header: Authorization: Bearer your_vapi_api_key_here

SSE (Deprecated)

• URL: https://mcp.vapi.ai/sse
• Header: Authorization: Bearer your_vapi_api_key_here

Available Tools

Assistants

Calls

Phone Numbers

Tools (Function Calling)

Authentication

Development

# Install dependencies
npm install

# Build
npm run build

# Test with MCP inspector
npm run inspector

Local Development Config

{
  "mcpServers": {
    "vapi-local": {
      "command": "node",
      "args": ["<path>/dist/index.js"],
      "env": {
        "VAPI_TOKEN": "<your_vapi_token>"
      }
    }
  }
}

Testing

# Unit tests (mocked)
npm run test:unit

# E2E tests (requires VAPI_TOKEN)
export VAPI_TOKEN=your_token_here
npm run test:e2e

# All tests
npm test

References

• Vapi Documentation
• Vapi Dashboard
• Vapi Remote MCP Server
• Model Context Protocol

Claude Code Setup (Recommended)

The easiest way to get started. No API key needed - authenticate via browser on first use.

1. Add MCP Server

claude mcp add vapi -- npx -y @vapi-ai/mcp-server

2. Install Skill (Optional)

The Vapi skill helps Claude guide you through building voice assistants:

mkdir -p ~/.claude/skills/vapi
curl -o ~/.claude/skills/vapi/SKILL.md https://raw.githubusercontent.com/VapiAI/mcp-server/main/skill/SKILL.md

3. Restart Claude Code

After restarting, use /vapi or ask Claude to help build a voice assistant. On first use, you'll be prompted to sign in via browser - no API key copy-paste needed.

Claude Desktop Setup

With OAuth (No API Key)

{
  "mcpServers": {
    "vapi": {
      "command": "npx",
      "args": ["-y", "@vapi-ai/mcp-server"]
    }
  }
}

With API Key

If you prefer to use an API key directly, get one from the Vapi dashboard:

{
  "mcpServers": {
    "vapi": {
      "command": "npx",
      "args": ["-y", "@vapi-ai/mcp-server"],
      "env": {
        "VAPI_TOKEN": "<your_vapi_token>"
      }
    }
  }
}

Remote Configuration

Connect to Vapi's hosted MCP server:

{
  "mcpServers": {
    "vapi": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://mcp.vapi.ai/mcp",
        "--header",
        "Authorization: Bearer ${VAPI_TOKEN}"
      ],
      "env": {
        "VAPI_TOKEN": "<your_vapi_token>"
      }
    }
  }
}

Example Usage

Create a Voice Assistant

Ask Claude:

I want to build a voice assistant that can schedule appointments

Make an Outbound Call

Call +1234567890 using my appointment reminder assistant with these details:
- Customer name: Sarah Johnson
- Appointment date: March 25th
- Appointment time: 2:30 PM

Schedule a Future Call

Schedule a call with my support assistant for next Tuesday at 3:00 PM to +1555123456