runDebuggerMode · BrowserTools MCP: Risk & Policy

WHAT IT DOES

What runDebuggerMode does on BrowserTools MCP

AI agents invoke runDebuggerMode to trigger actions in BrowserTools MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why runDebuggerMode needs a policy

Debugger mode allows stepping through code execution, inspecting variables, modifying runtime state, and triggering arbitrary code paths. This constitutes code execution capability that could be misused by an AI agent to inspect sensitive data, modify application behavior, or trigger unintended side effects.

From the tool's definition Tool name is 'runDebuggerMode' and description states it will 'debug an issue in our application'. Debugger mode enables execution of arbitrary code inspection, breakpoint setting, and inspection of application state through browser developer tools.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

runDebuggerMode Rate-limited

runDebuggerMode stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "runDebuggerMode": {
      "limits": [
        {
          "counter": "rundebuggermode_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches BrowserTools MCP, so you can run agents against it safely.

FAQ

Questions about runDebuggerMode

What does the runDebuggerMode tool do? +

Run debugger mode to debug an issue in our application. It is categorised as a Execute tool in the BrowserTools MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on runDebuggerMode? +

Register the BrowserTools MCP server in PolicyLayer and add a rule for runDebuggerMode: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches BrowserTools MCP. Nothing to install.

What risk level is runDebuggerMode? +

runDebuggerMode is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit runDebuggerMode? +

Yes. Add a rate_limit block to the runDebuggerMode rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block runDebuggerMode completely? +

Set action: deny in the PolicyLayer policy for runDebuggerMode. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides runDebuggerMode? +

runDebuggerMode is provided by the BrowserTools MCP server (sugatraj/cursor-browser-tools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.