MCP Hello World - MCP Server Mock for Testing
About
A minimal MCP server mock in TypeScript for testing MCP clients, supporting both STDIO and HTTP/SSE protocols.
Details
- License
- MIT
Explore
mcp-hello-world provides the following fixed capabilities for interaction and assertion in your tests:
Setting up with Highlight
This MCP is not yet compatible with Highlight’s one-click setup. However, you can still use it with Highlight by following these steps:
- Download and install Highlight from highlightai.com/download
- Navigate to the plugins tab and select "Add Custom Plugin"
-
Configure the plugin with the settings below
Plugin Name
MCP Hello World - MCP Server Mock for TestingCommand (node, npx, python, etc.)Please refer to the README for specific instructions on how to obtain API keys or other required environment variables.
- Enable "Start Automatically" if you want the plugin to start when Highlight launches
From the repository
Add this package as a dev dependency to your project:
``bash
You can programmatically start and stop the mcp-hello-world` server within your test framework (like Jest, Vitest, Mocha, etc.) for automated testing.
echo
Echoes back a message with 'Hello' prefix
debug
Lists all available tools and methods
add
Adds two numbers
- echo
- Description: Echoes the input message, prefixed with "Hello ".
- Method: tools/invoke
- Parameters: { name: 'echo', parameters: { message: string } }
- Returns: { content: [{ type: 'text', text: 'Hello {message}' }] } (e.g., { content: [{ type: 'text', text: 'Hello test' }] })
- debug
- Description: Lists all available MCP method definitions on the server.
- Method: tools/invoke
- Parameters: { name: 'debug', parameters: {} }
- Returns: A JSON structure containing definitions for all registered resources, tools, and prompts.
Claude Desktop / Cursor
Paste into your MCP client config file to install this server.
{
"mcpServers": {
"mcp hello world - mcp server mock for testing": {
"mcp-hello-world": {
"command": "npx",
"args": [
"mcp-hello-world"
]
}
}
}
}McpServers
{
"mcp-hello-world": {
"command": "npx",
"args": [
"mcp-hello-world"
]
}
}[![][npm-release-shield]][npm-release-link]
[![][npm-downloads-shield]][npm-downloads-link]
[![][github-action-test-shield]][github-action-test-link]
[![][github-action-release-shield]][github-action-release-link]
[github-action-release-link]: https://github.com/lobehub/mcp-hello-world/actions/workflows/release.yml
[github-action-release-shield]: https://img.shields.io/github/actions/workflow/status/lobehub/mcp-hello-world/release.yml?label=Release&logo=githubactions&logoColor=white&style=flat-square
[github-action-test-link]: https://github.com/lobehub/mcp-hello-world/actions/workflows/test.yml
[github-action-test-shield]: https://img.shields.io/github/actions/workflow/status/lobehub/mcp-hello-world/test.yml?label=Test&logo=githubactions&logoColor=white&style=flat-square
[npm-downloads-link]: https://www.npmjs.com/package/mcp-hello-world
[npm-downloads-shield]: https://img.shields.io/npm/dt/mcp-hello-world?label=Downloads&logo=npm&style=flat-square
[npm-release-link]: https://www.npmjs.com/package/mcp-hello-world
[npm-release-shield]: https://img.shields.io/npm/v/mcp-hello-world?logo=npm&style=flat-square
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:
```bash
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