agenticsorg/claude-plugin/mcp-integration

MCP Integration Tutorial

Build a Claude Code MCP server in 15 minutes.

What MCP gives you

Three primitives:

• Tools — callable functions (fetch_page(path))
• Resources — read-only URIs Claude can pull as context (agentics://about)
• Prompts — reusable instruction templates with arguments

A single server can expose any combination.

Minimal MCP server (Node)

import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
import { ListToolsRequestSchema, CallToolRequestSchema } from '@modelcontextprotocol/sdk/types.js';
const server = new Server(
  { name: 'my-server', version: '0.1.0' },
  { capabilities: { tools: {} } },
);
server.setRequestHandler(ListToolsRequestSchema, async () => ({
  tools: [{ name: 'hello', description: 'Say hi', inputSchema: { type: 'object' } }],
}));
server.setRequestHandler(CallToolRequestSchema, async req => ({
  content: [{ type: 'text', text: `Hello from ${req.params.name}` }],
}));
await server.connect(new StdioServerTransport());

Wire it into a plugin

Create .mcp.json at the plugin root:

{
  "mcpServers": {
    "my-server": {
      "command": "node",
      "args": ["${CLAUDE_PLUGIN_ROOT}/server.js"]
    }
  }
}

Test it locally: claude --plugin-dir ./plugins/my-plugin

Test the protocol directly

Drive the server with raw JSON-RPC over stdio:

echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"t","version":"1"}}}' | node server.js

You should see an initialize response with serverInfo and capabilities.

Common pitfalls

• `stdio` only: log to stderr, never stdout — stdout is the JSON-RPC channel
• Initialization order: client sends initialize, then notifications/initialized, then can call tools
• Schemas matter: tools without inputSchema will be rejected by some clients
• `isError`: return { isError: true, content: [...] } for tool errors instead of throwing — Claude can handle them gracefully

Reference

The agentics-org, agentics-events, agentics-blog, and agentics-projects plugins in this marketplace are all working MCP servers with different patterns (web scraping, REST API, GitHub graph). Read their server.js files.