Mcp Integration

• Plugin directory (always use for portability): { "command" : "${CLAUDE_PLUGIN_ROOT}/servers/my-server" } User environment variables
• From user's shell: { "env" : { "API_KEY" : "${MY_API_KEY}" , "DATABASE_URL" : "${DB_URL}" } } Best practice: Document all required environment variables in plugin README. 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 Using MCP Tools in Commands Pre-allow specific MCP tools in command frontmatter:

allowed-tools: [ "mcp plugin asana asana asana create task", "mcp plugin asana asana asana search tasks" ]

Wildcard (use sparingly):

allowed-tools: ["mcp plugin asana asana *"]

Best practice: Pre-allow specific tools, not wildcards, for security. Lifecycle Management Automatic startup: MCP servers start when plugin enables Connection established before first tool use Restart required for configuration changes Lifecycle: Plugin loads MCP configuration parsed Server process started (stdio) or connection established (SSE/HTTP/WS) Tools discovered and registered Tools available as mcp__plugin_...__... Viewing servers: Use /mcp command to see all servers including plugin-provided ones. 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. Token-Based (Headers) Static or environment variable tokens: { "type" : "http" , "url" : "https://api.example.com" , "headers" : { "Authorization" : "Bearer ${API_TOKEN}" } } Document required environment variables in README. Environment Variables (stdio) Pass configuration to MCP server: { "command" : "python" , "args" : [ "-m" , "my_mcp_server" ] , "env" : { "DATABASE_URL" : "${DB_URL}" , "API_KEY" : "${API_KEY}" , "LOG_LEVEL" : "info" } } Integration Patterns Pattern 1: Simple Tool Wrapper Commands use MCP tools with user interaction:

Command: create-item.md

allowed-tools: ["mcp plugin name server create _item"]

Steps:

1. Gather item details from user
2. Use mcp plugin_name_server create_ item
3. Confirm creation Use for: Adding validation or preprocessing before MCP calls. Pattern 2: Autonomous Agent Agents use MCP tools autonomously:

Agent: data-analyzer.md

Analysis Process: 1. Query data via mcp plugin db server query 2. Process and analyze results 3. Generate insights report Use for: Multi-step MCP workflows without user interaction. Pattern 3: Multi-Server Plugin Integrate multiple MCP servers: { "github" : { "type" : "sse" , "url" : "https://mcp.github.com/sse" } , "jira" : { "type" : "sse" , "url" : "https://mcp.jira.com/sse" } } Use for: Workflows spanning multiple services. 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 Batching Batch similar requests when possible:

Good: Single query with filters

tasks = search_tasks(project="X", assignee="me", limit=50)

Avoid: Many individual queries

for id in task_ids: task = get_task(id) Testing MCP Integration Local Testing Configure MCP server in .mcp.json Install plugin locally ( .claude-plugin/ ) Run /mcp to verify server appears Test tool calls in commands 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 Common Issues Server not connecting: Check URL is correct Verify server is running (stdio) Check network connectivity Review authentication configuration Tools not available: Verify server connected successfully Check tool names match exactly Run /mcp to see available tools Restart Claude Code after config changes Authentication failing: Clear cached auth tokens Re-authenticate Check token scopes and permissions Verify environment variables set Quick Reference MCP Server Types Type Transport Best For Auth stdio Process Local tools, custom servers Env vars SSE HTTP Hosted services, cloud APIs OAuth HTTP REST API backends, token auth Tokens ws WebSocket Real-time, streaming Tokens 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 Best Practices DO: ✅ Use ${CLAUDE_PLUGIN_ROOT} for portable paths ✅ Document required environment variables ✅ Use secure connections (HTTPS/WSS) ✅ Pre-allow specific MCP tools in commands ✅ Test MCP integration before publishing ✅ Handle connection and tool errors gracefully DON'T: ❌ Hardcode absolute paths ❌ Commit credentials to git ❌ Use HTTP instead of HTTPS ❌ Pre-allow all tools with wildcards ❌ Skip error handling ❌ Forget to document setup Additional Resources Reference Files For detailed information, consult: references/server-types.md

• Deep dive on each server type references/authentication.md
• Authentication patterns and OAuth references/tool-usage.md
• Using MCP tools in commands and agents 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 Implementation Workflow To add MCP integration to a plugin: Choose MCP server type (stdio, SSE, HTTP, ws) Create .mcp.json at plugin root with configuration Use ${CLAUDE_PLUGIN_ROOT} for all file references Document required environment variables in README Test locally with /mcp command Pre-allow MCP tools in relevant commands Handle authentication (OAuth or tokens) Test error cases (connection failures, auth errors) Document MCP integration in plugin README Focus on stdio for custom/local servers, SSE for hosted services with OAuth.