DevTool MCP — Claude Code MCP server: processes, proxy
Gives the agent a handle on your running app: dev-server control, a reverse proxy and frontend diagnostics. Comes in handy when UI work has to happen with the page in view.
claude mcp add devtool-mcp -- npx -y @standardbeagle/devtool-mcpWhat DevTool MCP does
DevTool MCP runs development processes and a proxy for you, and pulls diagnostics out of the frontend. The agent gets console errors, network requests and layout state from the live page instead of a written description.
It connects like any other MCP server and starts through npx. In Claude a single command is enough; Cursor and GitHub Copilot need a config entry with the command npx and the args -y plus @standardbeagle/devtool-mcp. There is no build step.
Node.js with npx on PATH is what the server launches through, so without both it will not come up. Check that before wiring it into an editor.
What it helps with
- start a dev server and proxy on the agent's request
- catch JavaScript errors on a live page
- inspect network requests without copying them out of DevTools
- check layout on a device through a tunnel
- hand the agent structured page data instead of prose
Example prompts for the agent
- Start the dev server for this project and show me the console errors in the browser
- Take a screenshot of the page and work out why the button sits off-screen
- Inspect the network requests on the checkout page
How to install DevTool MCP
Platform CLI
claude mcp add devtool-mcp -- npx -y @standardbeagle/devtool-mcpPlatform CLI
codex mcp add devtool-mcp -- npx -y @standardbeagle/devtool-mcpConfig file
{
"mcpServers": {
"devtool-mcp": {
"command": "npx",
"args": [
"-y",
"@standardbeagle/devtool-mcp"
]
}
}
}Config file
{
"servers": {
"devtool-mcp": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@standardbeagle/devtool-mcp"
]
}
}
}Platform CLI
gemini mcp add devtool-mcp npx -y @standardbeagle/devtool-mcpStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about DevTool MCP
How do I install DevTool MCP in Claude Code?
Run claude mcp add devtool-mcp -- npx -y @standardbeagle/devtool-mcp. The server is then registered in your Claude MCP configuration.
What does DevTool MCP do?
It manages dev processes, runs a reverse proxy and collects frontend diagnostics so the agent can see errors and network traffic from the running app.
What does the server need to run?
Node.js with npx available on PATH. The package is fetched through npx at startup, with no separate build.
