​
Unit testing

When initializing your MCP server, the CLI will also scaffold the necessary files to perform unit testing with Vitest. The tests are located in the test directory and should be named using the pattern [name].test.ts. To run the tests, you can use the following command: 
npm run test
Or, if you prefer using the @vitest/ui interface like we do: 
npm run test:ui

​
Using a MCP host

When running the dev command, the Vite plugin will create a .cursor/mcp.json file in the root of your project. This file will connect Cursor to your MCP server using the @mcplug/client package. You can also use this same JSON file to connect your MCP server to other AI clients like Claude.
If you have configured constants in your tools, you will need to set them in the mcp.json file inside the env property.For example, if your tool has a constant called _API_KEY, you would set it in the env property like this:
{
  "env": {
    "API_KEY": "your_api_key"
  }
}