mcp-integration

MCP Integration for Antigravity Plugins

Overview

Model Context Protocol (MCP) enables Antigravity plugins to integrate with external services and APIs by providing structured tool access. Use MCP integration to expose external service capabilities as tools within Antigravity.

Key capabilities:

• Connect to external services (databases, APIs, file systems)
• Provide 10+ related tools from a single service
• Handle OAuth and complex authentication flows
• Bundle MCP servers with plugins for automatic setup

MCP Server Configuration Methods

Plugins can bundle MCP servers in two ways:

Method 1: Dedicated .mcp.json (Recommended)

Create .mcp.json at plugin root:

{
  "database-tools": {
    "command": "${GEMINI_PLUGIN_ROOT}/servers/db-server",
    "args": ["--config", "${GEMINI_PLUGIN_ROOT}/config.json"],
    "env": {
      "DB_URL": "${DB_URL}"
    }
  }
}

Benefits:

• Clear separation of concerns
• Easier to maintain
• Better for multiple servers

Method 2: Inline in plugin.json

Add mcpServers field to plugin.json:

{
  "name": "my-plugin",
  "version": "1.0.0",
  "mcpServers": {
    "plugin-api": {
      "command": "${GEMINI_PLUGIN_ROOT}/servers/api-server",
      "args": ["--port", "8080"]
    }
  }
}

Benefits:

• Single configuration file
• Good for simple single-server plugins

MCP Server Types

stdio (Local Process)

Execute local MCP servers as child processes. Best for local tools and custom servers.

Configuration:

{
  "filesystem": {
    "command": "npx",
    "args": ["-y", "@modelcontextprotocol/server-filesystem", "/allowed/path"],
    "env": {
      "LOG_LEVEL": "debug"
    }
  }
}

Use cases:

• File system access
• Local database connections
• Custom MCP servers
• NPM-packaged MCP servers

Process management:

• Antigravity spawns and manages the process
• Communicates via stdin/stdout
• Terminates when Antigravity exits

SSE (Server-Sent Events)

Connect to hosted MCP servers with OAuth support. Best for cloud services.