Own MCP Server

A custom Model Context Protocol (MCP) server, built from scratch in Node.js using the official @modelcontextprotocol/sdk. It runs over stdio and exposes four real, working tools that any MCP-compatible client (Claude Desktop, Claude Code, the MCP Inspector, etc.) can call.

This isn't a toy/hello-world stub — every tool actually does something:

Project structure

own-mcp-server/
├── src/
│   ├── index.js              # Server entry point — registers tools, connects stdio transport
│   └── tools/
│       ├── calculator.js     # calculate
│       ├── time.js           # get_current_time
│       ├── weather.js        # get_weather (live API call)
│       └── notes.js          # add_note / list_notes / delete_note (persisted to disk)
├── test/
│   └── test-server.mjs       # End-to-end test: spawns the server and drives it with a real MCP client
├── data/
│   └── .gitkeep              # notes.json is created here at runtime (gitignored)
├── .github/workflows/test.yml# CI: runs the test suite on every push/PR
├── claude_desktop_config.example.json
├── package.json
├── .gitignore
├── LICENSE
└── README.md

Related MCP server: MCP TypeScript Tools Server

How it works

1. McpServer from the SDK is instantiated once in src/index.js.

2. Each file in src/tools/ exports a register*Tool(server) function that calls server.registerTool(name, schema, handler) to add one or more tools.

3. src/index.js imports and calls each of those registration functions, then connects the server to a StdioServerTransport — this is what lets Claude Desktop / Claude Code talk to it as a subprocess over stdin/stdout.

4. Input validation for every tool is done with Zod schemas, so malformed calls are rejected with a clear error before your handler code ever runs.

Requirements

• Node.js 18 or newer

• npm

Setup

git clone https://github.com/mayo-byte07/OWN-MCP-SERVER.git
cd OWN-MCP-SERVER
npm install

Running it

You normally don't run this directly — an MCP client launches it as a subprocess. But you can smoke-test it standalone:

npm start

You should see own-mcp-server running on stdio printed to stderr. The process will then sit waiting for MCP protocol messages on stdin — that's expected; press Ctrl+C to stop it.

Testing it

An automated end-to-end test spawns the real server, connects a real MCP client to it, and calls every tool:

npm test

Expected output includes a listing of all six tools and a successful call to each one (calculate, get_current_time, add_note, list_notes, delete_note, get_weather).

You can also poke at it interactively with the official MCP Inspector:

npm run inspect

This opens a web UI where you can call each tool by hand and see the raw request/response.

Connecting it to Claude Desktop

1. Open your Claude Desktop config file:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

   • Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Add an entry like the one in claude_desktop_config.example.json, pointing args at the absolute path to src/index.js on your machine:

   {
     "mcpServers": {
       "own-mcp-server": {
         "command": "node",
         "args": ["/absolute/path/to/OWN-MCP-SERVER/src/index.js"]
       }
     }
   }

3. Restart Claude Desktop. The four tools should now show up under the 🔌 tools icon in a new conversation.

Connecting it to Claude Code

claude mcp add own-mcp-server -- node /absolute/path/to/OWN-MCP-SERVER/src/index.js

Extending it

To add a new tool:

1. Create a new file in src/tools/, e.g. src/tools/mytool.js.

2. Export a function that registers it:

   import { z } from "zod";
   
   export function registerMyTool(server) {
     server.registerTool(
       "my_tool",
       {
         title: "My Tool",
         description: "What it does.",
         inputSchema: { someInput: z.string().describe("What this argument is for") },
       },
       async ({ someInput }) => {
         return { content: [{ type: "text", text: `You said: ${someInput}` }] };
       }
     );
   }

3. Import and call it in src/index.js alongside the others.

4. Add a case for it in test/test-server.mjs so CI keeps covering it.

Why stdio and not HTTP?

Stdio transport is the simplest and most common way to run a local MCP server — the client launches your script as a child process and talks to it over stdin/stdout, so there's no port, no auth, and no network exposure to manage. If you need a remote/shared server later, the SDK also supports an HTTP + SSE transport (StreamableHTTPServerTransport) — see the SDK docs for that setup.

License

MIT — see LICENSE.