xsmcp

# xsMCP > extra-small MCP SDK for mcp builders hating bloat. > [!CAUTION] > xsMCP has been sunset > > Due to frequent MCP updates and a lack of actual users for xsMCP, we archived xsMCP in July 2025. > > If MCP is stable enough and there is user interest, we may restart this project. ## About ### Why is there this project? [`@modelcontextprotocol/sdk` is large](https://pkg-sized.dev/@modelcontextprotocol/sdk) and has dependencies on libraries like `zod`, `express`, etc. that you probably don't even want to use. Like [xsAI](https://github.com/moeru-ai/xsai), xsMCP does not force you to use a particular server or schema library and is very small. ### Roadmap Our current target is Streamable HTTP Client / Server, Stdio have lower priority. ### Compatibility xsMCP v0.1 is targeted to be compatible with the `2025-03-26` revision and is not backward compatible. ### HTTP Server Structure `@xsmcp/server-http` is based on [Web Standards](https://hono.dev/docs/concepts/web-standard), not Express. ```ts import { createFetch } from '@xsmcp/server-http' import { createServer } from '@xsmcp/server-shared' import { serve } from 'srvx' import * as tools from '...' const server = createServer({ ...options }) for (const tool of tools) { server.addTool(tool) } // (req: Request) => Promise<Response> const fetch = createFetch(server) // node.js, deno, bun serve({ fetch }) // cloudflare workers, pages export default { fetch } ``` It can be used as a server on its own or with `hono`, `elysia` and `itty-router` for more features: ```ts import { createFetch } from '@xsmcp/server-http' import { createServer } from '@xsmcp/server-shared' import { Elysia } from 'elysia' import { Hono } from 'hono' import { AutoRouter } from 'itty-router' import * as tools from '...' const server = createServer({ ...options }) for (const tool of tools) { server.addTool(tool) } const fetch = createFetch(server) // hono new Hono() .post('/mcp', ({ req }) => fetch(req.raw)) // elysia new Elysia() .post('/mcp', ({ request }) => fetch(request)) // itty-router AutoRouter() .post('/mcp', req => fetch(req)) ``` At the same time, it does not depends on any server framework thus minimizing the size. For simplicity reasons, this server only returns JSON Response, not SSE. ## License [MIT](LICENSE.md) ### Third Party Licenses This project partially copies code from the following projects: | Project | License | | -- | -- | | [modelcontextprotocol/specification](https://github.com/modelcontextprotocol/specification) | [MIT](https://github.com/modelcontextprotocol/specification/blob/main/LICENSE) | | [modelcontextprotocol/servers](https://github.com/modelcontextprotocol/servers) | [MIT](https://github.com/modelcontextprotocol/servers/blob/main/LICENSE) | | [modelcontextprotocol/typescript-sdk](https://github.com/modelcontextprotocol/typescript-sdk) | [MIT](https://github.com/modelcontextprotocol/typescript-sdk/blob/main/LICENSE) | | [crouchcd/pkce-challenge](https://github.com/crouchcd/pkce-challenge) | [MIT](https://github.com/crouchcd/pkce-challenge/blob/master/LICENSE) | | [denoland/std](https://github.com/denoland/std) | [MIT](https://github.com/denoland/std/blob/main/LICENSE) |