How to Integrate Custom Tools into Claude Code with MCP Server in 5 Minutes¶

Target Audience

Intermediate engineers looking to integrate custom tools with Claude Code

Key Points¶

Launch an MCP server locally
Call custom tools from Claude Code
Integrate tools into existing workflows

Why This Matters Now¶

Since Claude Code 2.0, Model Context Protocol (MCP) support has standardized external tool integration. However, official documentation lacks concrete implementation steps, leaving many developers struggling with integration. This article presents a minimal working MCP server implementation.

Implementation Steps Overview¶

Step	Content	Success Metric
1	Implement MCP server	Server starts successfully
2	Add Claude configuration	Tool recognized
3	Verify operation	Tool executes successfully

Step 1: Implement Minimal MCP Server¶

Implement a minimal MCP server in TypeScript. Using @modelcontextprotocol/sdk, you can build a working server in just 10 lines.

import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';

const server = new Server({
  name: 'my-tool',
  version: '1.0.0',
}, { capabilities: { tools: {} } });

server.setRequestHandler('tools/list', async () => ({
  tools: [{
    name: 'echo',
    description: 'Echo input text',
    inputSchema: { type: 'object', properties: { text: { type: 'string' } } }
  }]
}));

server.setRequestHandler('tools/call', async (request) => {
  const { name, arguments: args } = request.params;
  if (name === 'echo') return { content: [{ type: 'text', text: `Echo: ${args.text}` }] };
});

await server.connect(new StdioServerTransport());

Step 2: Update Claude Configuration¶

Register the MCP server in ~/.claude/claude_desktop_config.json. This configuration allows Claude Code to auto-start the server.

{
  "mcpServers": {
    "my-tool": {
      "command": "node",
      "args": ["/path/to/mcp-server.js"],
      "env": {}
    }
  }
}

Step 3: Verify Execution from Claude Code¶

After restarting Claude Code, the new tool becomes available. Type /tools in the prompt to see the echo tool listed.

# Verification command
echo "test" | claude code --tool echo

Common Pitfalls and Solutions¶

Symptom	Cause	Immediate Solution
Tool not displayed	Config file path error	Use absolute path
Server startup error	Node.js not installed	Install v20+
Connection timeout	Port conflict	Use StdioTransport

Advanced Configuration

Advanced MCP server features include streaming responses, async processing, and error handling. For production environments, consider adding: - Retry logic implementation - Logging mechanism - Authentication token validation