MCP Js Debugger MCP Server

MCP server exposing Chrome DevTools Protocol debugging capabilities

Local serverstdioTypeScript

What is the MCP Js Debugger MCP server?

MCP server exposing Chrome DevTools Protocol debugging capabilities. Exposed over MCP by the mcp js debugger mcp server, that capability becomes something an assistant can invoke while it works, not something you go and do afterwards.

What it actually does

An MCP (Model Context Protocol) server that exposes Chrome DevTools Protocol debugging capabilities, enabling AI assistants to debug JavaScript and TypeScript applications.

  • Connect to any CDP-compatible debugger (Node.js, Chrome, Edge)
  • Set, list, and remove breakpoints
  • Step through code (over, into, out)
  • Inspect call stacks with source map support
  • Evaluate expressions in any stack frame
  • View and modify variables

Its toolset

Everything the assistant can do here goes through one of these:

  • connect_debugger — Connect to a CDP endpoint via WebSocket URL
  • disconnect_debugger — Disconnect from a debugging session
  • set_breakpoint — Set a breakpoint by URL and line number
  • remove_breakpoint — Remove a breakpoint by ID
  • list_breakpoints — List all breakpoints in a session
  • resume_execution — Resume execution after pause
  • step_over — Step over the current statement
  • step_into — Step into a function call
  • step_out — Step out of the current function
  • pause_execution — Pause running execution
  • get_call_stack — Get the current call stack with source locations
  • evaluate_expression — Evaluate a JavaScript expression

Configuration

  • Node.js 18.0.0 or later - A CDP-compatible debug target (Node.js, Chrome, Edge, etc.)

Adding it to your client

The server ships on npm as mcp-js-debugger, so your MCP client can launch it on demand — there is no separate build step. Add the server block to your client's configuration, restart it, and the tools register themselves.

When to reach for it

This sits in the developer tooling group, where several servers overlap in what they claim to do but differ sharply once you actually set them up. MCP Js Debugger's toolset — connect_debugger, disconnect_debugger, set_breakpoint and 11 more — is a fair guide to whether it matches your workflow. It is maintained by johngrimes; worth a glance at recent repository activity before you build anything load-bearing on it.

We check each listing at SyncDev against the project's documentation before it goes live — if something here drifts out of date, it is a bug worth reporting.

Caveats

  • It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
  • With 14 tools registered it takes up a noticeable share of the context window; turn it off in projects that never touch MCP Js Debugger.
  • MCP clients confirm each tool call by default. Leave that on until you have watched what the mcp js debugger mcp server does with a few real requests.

Available tools

ToolWhat it does
connect_debuggerConnect to a CDP endpoint via WebSocket URL
disconnect_debuggerDisconnect from a debugging session
set_breakpointSet a breakpoint by URL and line number
remove_breakpointRemove a breakpoint by ID
list_breakpointsList all breakpoints in a session
resume_executionResume execution after pause
step_overStep over the current statement
step_intoStep into a function call
step_outStep out of the current function
pause_executionPause running execution
get_call_stackGet the current call stack with source locations
evaluate_expressionEvaluate a JavaScript expression
get_scope_variablesGet variables in a scope
set_variable_valueModify a variable's value

How to install the MCP Js Debugger MCP server

Or add to `.mcp.json`:

```json
{
  "mcpServers": {
    "mcp-js-debugger": {
      "command": "npx",
      "args": ["mcp-js-debugger"]
    }
  }
}

Configuration as documented by the project. Restart the client after saving.

Configuration

  • Node.js 18.0.0 or later - A CDP-compatible debug target (Node.js, Chrome, Edge, etc.)

Example prompts to try

  • Use MCP Js Debugger to connect debugger.
  • Use MCP Js Debugger to disconnect debugger.
  • Use MCP Js Debugger to set breakpoint.

Frequently asked questions

It connects MCP Js Debugger to MCP-compatible AI assistants such as Claude and Cursor, exposing 14 tools (connect_debugger, disconnect_debugger, set_breakpoint, and more) that the assistant can call on your behalf. Instead of copying data back and forth by hand, the assistant works with MCP Js Debugger directly.