MCP Server - JavaScript SDK

What is MCP Server - JavaScript SDK?

MCP Server - JavaScript SDK is an unofficial JavaScript SDK for the Model Context Protocol (MCP). It allows developers to create MCP servers by defining prompts, resources, and tools using plain JavaScript.

How to use MCP Server - JavaScript SDK?

Install the package via npm (npm install mcp-js-server). Create separate modules to export prompts, resources, and tools, then import them and instantiate a server with the MCP constructor, providing server name and version. Server logs are written to standard system log directories.

Key features of MCP Server - JavaScript SDK

• Define prompts, resources, and tools in JavaScript
• Supports async tool handlers with JSON Schema validation
• Lightweight, unofficial implementation of the MCP spec
• Available as an npm package (mcp-js-server)
• Logs stored in platform‑specific system directories

Use cases of MCP Server - JavaScript SDK

• Build a demo MCP server with a simple “hello world” prompt
• Expose an external OpenAPI specification as a resource
• Create tools that return dynamic data (e.g., current date)
• Process complex tool inputs using schemas and async handlers
• Rapidly prototype custom MCP servers in JavaScript

FAQ from MCP Server - JavaScript SDK

Is this the official JavaScript SDK for MCP?

No, this is an unofficial implementation of the Model Context Protocol.

How do I install the package?

Install it using npm: npm install mcp-js-server.

Where can I find server logs?

Logs are stored in your user system logs directory:

• Linux: ~/.local/share/logs
• macOS: ~/Library/Logs
• Windows: %USERPROFILE%\AppData\Local\Logs

How do I define tools in the SDK?

Export an object where each key is a tool name. Each tool must include description, handler (an async function), and schema (a JSON Schema object defining parameters).