Vapi MCP Server

Build AI voice assistants and phone agents with Vapi using the 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

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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:

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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)

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{
  "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:

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{
  "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:

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{
  "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:

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I want to build a voice assistant that can schedule appointments

Make an Outbound Call

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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

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

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

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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

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# Install dependencies
npm install

# Build
npm run build

# Test with MCP inspector
npm run inspector

Local Development Config

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

Testing

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# 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