First, add this file if you're using Claude Desktop: code ~/Library/Application\ Support/Claude/claude_desktop_config.json. Copy the absolute path from which node and from react/compiler/react-mcp-server/dist/index.js and paste, for example:

{
  "mcpServers": {
    "react": {
      "command": "/Users/<username>/.asdf/shims/node",
      "args": [
        "/Users/<username>/code/react/compiler/packages/react-mcp-server/dist/index.js"
      ]
    }
  }
}

Next, run yarn workspace react-mcp-server watch from the react/compiler directory and make changes as needed. You will need to restart Claude everytime you want to try your changes.