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

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.

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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>"
      }
    }
  }
}

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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

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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.

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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

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Available Tools

Assistants

Tool	Description
vapi_list_assistants	List all assistants
vapi_get_assistant	Get assistant by ID
vapi_create_assistant	Create new assistant
vapi_update_assistant	Update assistant
vapi_delete_assistant	Delete assistant

Calls

Tool	Description
vapi_list_calls	List call history
vapi_get_call	Get call details
vapi_create_call	Start outbound call (immediate or scheduled)

Phone Numbers

Tool	Description
vapi_list_phone_numbers	List phone numbers
vapi_get_phone_number	Get phone number details
vapi_buy_phone_number	Purchase new number
vapi_update_phone_number	Update number settings
vapi_delete_phone_number	Release number

Tools (Function Calling)

Tool	Description
vapi_list_tools	List custom tools
vapi_get_tool	Get tool details
vapi_create_tool	Create tool for API integration
vapi_update_tool	Update tool
vapi_delete_tool	Delete tool

Authentication

Tool	Description
vapi_login	Start OAuth flow
vapi_logout	Log out and clear credentials

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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

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References

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