emulate_cpu · Chrome DevTools MCP: Risk & Policy

WHAT IT DOES

What emulate_cpu does on Chrome DevTools MCP

AI agents invoke emulate_cpu to trigger actions in Chrome DevTools 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 emulate_cpu needs a policy

This tool executes a command that alters the runtime behavior of a live browser page. While the effect is reversible (throttling can be removed), it is an active operation that triggers Chrome DevTools to modify system-level performance settings on the inspected process.

From the tool's definition Tool performs 'emulates CPU throttling by slowing down the selected page' — actively manipulates browser/page behavior via DevTools protocol, triggering external effects (performance degradation) that depend on the throttling parameters chosen.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

emulate_cpu Rate-limited

emulate_cpu 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": {
    "emulate_cpu": {
      "limits": [
        {
          "counter": "emulate_cpu_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 Chrome DevTools MCP, so you can run agents against it safely.

FAQ

Questions about emulate_cpu

What does the emulate_cpu tool do? +

Emulates CPU throttling by slowing down the selected page. It is categorised as a Execute tool in the Chrome DevTools 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 emulate_cpu? +

Register the Chrome DevTools MCP server in PolicyLayer and add a rule for emulate_cpu: 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 Chrome DevTools MCP. Nothing to install.

What risk level is emulate_cpu? +

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

Can I rate-limit emulate_cpu? +

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

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

emulate_cpu is provided by the Chrome DevTools MCP server (shay5555-gif/chrome-devtools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.