screencast_stop · Chrome Devtools MCP: Risk & Policy

WHAT IT DOES

What screencast_stop does on Chrome Devtools

AI agents invoke screencast_stop to trigger actions in Chrome Devtools. 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 screencast_stop needs a policy

This tool executes a command to stop a recording, making it an Execute category action rather than Read (which would be passive inspection) or Write (which would modify persistent data). The severity is low because stopping a screencast has minimal blast radius—it cannot damage data, cause financial harm, or delete information.

From the tool's definition Tool stops an active screencast recording via Chrome DevTools control. The description states it 'Stops the active screencast recording on the selected page,' which is an operation that triggers a DevTools action with external effects (halting a recording…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

screencast_stop Rate-limited

screencast_stop 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": {
    "screencast_stop": {
      "limits": [
        {
          "counter": "screencast_stop_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, so you can run agents against it safely.

FAQ

Questions about screencast_stop

What does the screencast_stop tool do? +

Stops the active screencast recording on the selected page. It is categorised as a Execute tool in the Chrome Devtools MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on screencast_stop? +

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

What risk level is screencast_stop? +

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

Can I rate-limit screencast_stop? +

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

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

screencast_stop is provided by the Chrome Devtools MCP server (zhang77-x/chrpme_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.