mcp-hello-world

What it does

A minimal MCP server written in TypeScript designed as a test double for unit and integration testing. It exposes simple, predictable tools (like echo and debug) with fixed behaviors, and supports both STDIO and HTTP/SSE transport protocols. It is not intended for production use.

Who it's for

Developers testing MCP client implementations who need a lightweight, controllable mock server. Useful when you want to validate client logic without depending on network availability or the complexity of a real backend.

Common use cases

• Mock server for unit and integration tests of MCP client code
• Test both STDIO and HTTP/SSE transport implementations in isolation
• Debug client behavior against predictable tool responses
• Run MCP clients in CI/CD environments without external dependencies
• Validate protocol compliance in test frameworks (Jest, Vitest, Mocha)

Setup pitfalls

• STDIO mode requires Node.js and npx; HTTP/SSE mode requires cloning the repository and running pnpm build and pnpm start:http locally.
• Last commit was 343 days ago with no CI automation; update frequency and maintenance status should be verified before adoption.
• Explicitly not for production—this is a test-only tool with no guarantees about stability or long-term support.