litemcp

# LiteMCP A TypeScript framework for building MCP (Model Context Protocol) servers elegantly > **Deprecate notice**: > > Since the [official SDK](https://github.com/modelcontextprotocol/typescript-sdk) already offers a high-level API similar to this project, this project will no longer be maintained. > > If you like the CLI commands in this project, you can use them independently: https://github.com/wong2/mcp-cli ## Features - Simple Tool, Resource, Prompt definition - Full TypeScript support - Built-in [logging](#logging) - Built-in error handling - Built-in CLI for [testing and debugging](#debugging-with-mcp-cli) - Built-in support for [SSE transport](#sse-transport) ## Installation ```bash npm install litemcp zod ``` ## Quickstart ```js import { LiteMCP } from "litemcp"; import { z } from "zod"; const server = new LiteMCP("demo", "1.0.0"); server.addTool({ name: "add", description: "Add two numbers", parameters: z.object({ a: z.number(), b: z.number(), }), execute: async (args) => { return args.a + args.b; }, }); server.addResource({ uri: "file:///logs/app.log", name: "Application Logs", mimeType: "text/plain", async load() { return { text: "Example log content", }; }, }); server.start(); ``` You can test the server in terminal with: ```bash npx litemcp dev server.js ``` ## Core Concepts ### Tools Tools in MCP allow servers to expose executable functions that can be invoked by clients and used by LLMs to perform actions. ```js server.addTool({ name: "fetch", description: "Fetch the content of a url", parameters: z.object({ url: z.string(), }), execute: async (args) => { const content = await fetchWebpageContent(args.url); return content; }, }); ``` ### Resources Resources represent any kind of data that an MCP server wants to make available to clients. This can include: - File contents - Screenshots and images - Log files - And more Each resource is identified by a unique URI and can contain either text or binary data. ```js server.addResource({ uri: "file:///logs/app.log", name: "Application Logs", mimeType: "text/plain", async load() { return { text: await readLogFile(), }; }, }); ``` You can also return binary contents in `load`: ```js async load() { return { blob: 'base64-encoded-data' } } ``` ### Prompts Prompts enable servers to define reusable prompt templates and workflows that clients can easily surface to users and LLMs. They provide a powerful way to standardize and share common LLM interactions. ```js server.addPrompt({ name: "git-commit", description: "Generate a Git commit message", arguments: [ { name: "changes", description: "Git diff or description of changes", required: true, }, ], load: async (args) => { return `Generate a concise but descriptive commit message for these changes:\n\n${args.changes}`; }, }); ``` ### Logging You can send log messages to the client with `server.logger` ```js server.addTool({ name: "download", description: "Download a file from a url", parameters: z.object({ url: z.string(), }), execute: async (args) => { server.logger.info("Downloading file", { url: args.url }); // ... server.logger.info("Downloaded file", { url: args.url }); return response; }, }); ``` The `logger` object has the following methods: - `debug(message: string, context?: JsonValue)` - `info(message: string, context?: JsonValue)` - `warn(message: string, context?: JsonValue)` - `error(message: string, context?: JsonValue)` ## Running Your Server ### Debugging with `mcp-cli` The fastest way to test and debug your server is with [`mcp-cli`](https://github.com/wong2/mcp-cli): ```bash npx litemcp dev server.js npx litemcp dev server.ts // ts files are also supported ``` This will run your server with `mcp-cli` for testing and debugging your MCP server in the terminal. ### Inspect with `MCP Inspector` Another way is to use the official [`MCP Inspector`](https://modelcontextprotocol.io/docs/tools/inspector) to inspect your server with a Web UI: ```bash npx litemcp inspect server.js ``` ### SSE Transport The servers are running with `stdio` transport by default. You can also run the server with SSE mode: ```js server.start({ transportType: "sse", sse: { endpoint: "/sse", port: 8080, }, }); ``` This will start the server and listen for SSE connections on http://localhost:8080/sse. You can then connect to the server with [SSE transport](https://modelcontextprotocol.io/docs/concepts/transports#server-sent-events-sse) in the client. ## Showcase > If you've developed a server using LiteMCP, please submit a PR to showcase it here! - https://github.com/wong2/mcp-jina-reader - https://github.com/nloui/paperless-mcp ## Roadmap - Add support for Resource Templates ## Related - [mcp-cli](https://github.com/wong2/mcp-cli) - A CLI for testing and debugging MCP servers - [mcpservers.org](https://mcpservers.org) - A curated list of MCP servers - [FastMCP](https://github.com/jlowin/fastmcp) - A Python library for MCP server development, inspiration for this project