lobehub/mcp-hello-world

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This is a **minimal Model Context Protocol (MCP) server** implemented in TypeScript, primarily intended to serve as a **Test Double / Mock Server**.
**Core Purpose**: To provide a lightweight, controllable, and predictable MCP server environment for **unit testing** or **integration testing** client code that needs to interact with an MCP server.
**Note:** This project is **not suitable for production environments** or deployment as a general-purpose MCP server.
Why Use mcp-hello-world in Tests?
When testing code related to MCP clients, you usually don't want to depend on a real, potentially complex, and unpredictably responsive AI backend service. Using mcp-hello-world as a test double offers several advantages:
1. **Isolation**: Focus your tests on client logic without worrying about network issues or the availability of the real server.
2. **Predictability**: The provided echo and debug tools have simple, fixed behaviors, making it easy to write assertions.
3. **Speed**: Fast startup and response times, suitable for frequent use in unit tests.
4. **Lightweight**: Few dependencies, easy to integrate into test environments.
5. **Protocol Coverage**: Supports both STDIO and HTTP/SSE MCP transport protocols, allowing you to test client behavior under different connection methods.
Installation
Add this package as a **dev dependency** to your project:
Manual Execution (for Debugging Tests)
You might want to run the server manually sometimes to debug your tests or client behavior.
STDIO Mode
This is the simplest way to run, especially during local development and debugging.
The server will listen on standard input and output MCP responses to standard output. You can use tools like MCP Inspector to connect to the process.
To configure this server in your MCP client, add the following to your configuration:
HTTP/SSE Mode
If you need to debug via a network interface or test HTTP-based MCP clients.