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MCP Node.js Debugger MCP Server

Enables Cursor and Claude Code to debug Node.js processes at runtime via MCP with in-process inspection and breakpoints.

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Installation

Add the following to your MCP client configuration file.

Configuration

View docs

{
    "mcpServers": {
        "cursor_nodejs_debugger": {
            "command": "npx",
            "args": [
                "@hyperdrive-eng/mcp-nodejs-debugger"
            ]
        }
    }
}

You can debug Node.js applications at runtime by attaching Cursor or Claude Code to a dedicated MCP server that exposes debugging capabilities. This MCP Node.js Debugger lets you set breakpoints, inspect runtime state, and step through code in a running Node.js process that is started with the inspect flag. It is designed to work with the MCP toolchain to streamline live debugging in your local development workflow.

How to use

You enable debugging in your Node.js server by starting the process with the inspect flag, then connect your MCP client to the debugger server. Use Cursor to add the MCP server configuration and to manage the connection, or use Claude Code to add the MCP server and issue debugging commands from your chat-driven workflow.

Once connected, you can set breakpoints at runtime, inspect variables and state, and run targeted commands to check values or reproduce error conditions. The debugging commands are exposed through the MCP runtime endpoints and appear as actions you can invoke from Cursor or Claude Code.

How to install

Prerequisites you need installed on your machine before starting: Node.js (including npm or npx), and an MCP client setup for Cursor or Claude Code.

# Prerequisites
node -v
npm -v

# Example Node.js project start with debugging enabled
node --inspect {file.js}
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Configuration and usage notes

Two MCP server connection methods are provided for this debugger: a Cursor-based local server entry and a Claude Code-based local server entry. Each method uses the same underlying MCP server executable and is configured as a stdio server.

Below are the explicit configuration blocks shown in usage examples. Use these exactly as your MCP server configuration to enable the debugger client.

Troubleshooting and tips

If you start your Node.js process with --inspect and the debugger cannot attach, verify that the process is running and that the port is accessible. Check that you connected to the correct MCP server name and that you have an active connection in your MCP client. If you encounter authentication or network whitelisting issues, ensure your environment allows the MCP debugger to communicate with the tools you are using.

Available tools

set_breakpoint

Set a breakpoint in a specific file and line within the Node.js process being debugged.

list_breakpoints

List all active breakpoints currently set in the Node.js debug session.

nodejs_inspect

Evaluate JavaScript code in the Node.js runtime to inspect variables, state, or perform lightweight checks during debugging.