stepIn · MCP Chrome Debugger Protocol MCP: Risk & Policy

WHAT IT DOES

What stepIn does on MCP Chrome Debugger Protocol

AI agents invoke stepIn to trigger actions in MCP Chrome Debugger Protocol. 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 stepIn needs a policy

stepIn controls execution flow of a running Node.js process via the Chrome DevTools Protocol, advancing the debugger into the next function call. This triggers external execution behavior in the target process, making it an Execute-category action. Misuse could cause the process to execute unintended code paths, hence medium severity.

From the tool's definition Step into function call (DAP standard name)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stepIn Rate-limited

stepIn 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": {
    "stepIn": {
      "limits": [
        {
          "counter": "stepin_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 MCP Chrome Debugger Protocol, so you can run agents against it safely.

FAQ

Questions about stepIn

What does the stepIn tool do? +

Step into function call (DAP standard name). It is categorised as a Execute tool in the MCP Chrome Debugger Protocol MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on stepIn? +

Register the MCP Chrome Debugger Protocol MCP server in PolicyLayer and add a rule for stepIn: 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 MCP Chrome Debugger Protocol. Nothing to install.

What risk level is stepIn? +

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

Can I rate-limit stepIn? +

Yes. Add a rate_limit block to the stepIn 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 stepIn completely? +

Set action: deny in the PolicyLayer policy for stepIn. 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 stepIn? +

stepIn is provided by the MCP Chrome Debugger Protocol MCP server (vitalyostanin/mcp-chrome-debugger-protocol). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.