MCP Integration

MCP Integration for Claude Code Plugins

Overview

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

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:

MCP Server Types

MCP Tool Naming

When MCP servers provide tools, they're automatically prefixed:

Format: mcp__plugin_<plugin-name>_<server-name>__<tool-name>

Example:

• Plugin: asana
• Server: asana
• Tool: create_task
• Full name: mcp__plugin_asana_asana__asana_create_task

Authentication Patterns

OAuth (SSE/HTTP)

OAuth handled automatically by Claude Code:

{
  "type": "sse",
  "url": "https://mcp.example.com/sse"
}

User authenticates in browser on first use. No additional configuration needed.

Integration Patterns

Security Best Practices

Use HTTPS/WSS

Always use secure connections:

✅ "url": "https://mcp.example.com/sse"
❌ "url": "http://mcp.example.com/sse"

Token Management

DO:

• ✅ Use environment variables for tokens
• ✅ Document required env vars in README
• ✅ Let OAuth flow handle authentication

DON'T:

• ❌ Hardcode tokens in configuration
• ❌ Commit tokens to git
• ❌ Share tokens in documentation

Permission Scoping

Pre-allow only necessary MCP tools:

✅ allowed-tools: [
  "mcp__plugin_api_server__read_data",
  "mcp__plugin_api_server__create_item"
]

❌ allowed-tools: ["mcp__plugin_api_server__*"]

Error Handling

Connection Failures

Handle MCP server unavailability:

• Provide fallback behavior in commands
• Inform user of connection issues
• Check server URL and configuration

Tool Call Errors

Handle failed MCP operations:

• Validate inputs before calling MCP tools
• Provide clear error messages
• Check rate limiting and quotas

Configuration Errors

Validate MCP configuration:

• Test server connectivity during development
• Validate JSON syntax
• Check required environment variables

Performance Considerations

Lazy Loading

MCP servers connect on-demand:

• Not all servers connect at startup
• First tool use triggers connection
• Connection pooling managed automatically

Testing MCP Integration

Local Testing

1. Configure MCP server in .mcp.json
2. Install plugin locally (.claude-plugin/)
3. Run /mcp to verify server appears
4. Test tool calls in commands
5. Check claude --debug logs for connection issues

Validation Checklist

• MCP configuration is valid JSON
• Server URL is correct and accessible
• Required environment variables documented
• Tools appear in /mcp output
• Authentication works (OAuth or tokens)
• Tool calls succeed from commands
• Error cases handled gracefully

Debugging

Enable Debug Logging

claude --debug

Look for:

• MCP server connection attempts
• Tool discovery logs
• Authentication flows
• Tool call errors

MCP Server Types

Configuration Checklist

• Server type specified (stdio/SSE/HTTP/ws)
• Type-specific fields complete (command or url)
• Authentication configured
• Environment variables documented
• HTTPS/WSS used (not HTTP/WS)
• ${CLAUDE_PLUGIN_ROOT} used for paths

Additional Resources

Example Configurations

Working examples in examples/:

• stdio-server.json - Local stdio MCP server
• sse-server.json - Hosted SSE server with OAuth
• http-server.json - REST API with token auth

External Resources

• Official MCP Docs: https://modelcontextprotocol.io/
• Claude Code MCP Docs: https://docs.claude.com/en/docs/claude-code/mcp
• MCP SDK: @modelcontextprotocol/sdk
• Testing: Use claude --debug and /mcp command

Full Specification

Complete details, decision trees, protocols, and implementation specs: references/full-details.md