wait_for · Chrome Devtools MCP: Risk & Policy

WHAT IT DOES

What wait_for does on Chrome Devtools

AI agents invoke wait_for 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 wait_for needs a policy

This tool executes conditional logic that monitors browser state and controls program flow based on DOM changes. While it doesn't directly modify data or execute arbitrary code, it triggers external operations (Chrome browser polling) whose effects depend on the specified text parameter. It's more than a simple Read (which would be passive inspection) because it actively controls execution flow and timing.

From the tool's definition Tool description states 'Wait for the specified text to appear on the selected page' - this indicates polling/monitoring behavior that blocks execution flow and interacts with a live Chrome browser session to detect dynamic content changes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

wait_for Rate-limited

wait_for 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": {
    "wait_for": {
      "limits": [
        {
          "counter": "wait_for_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 wait_for

What does the wait_for tool do? +

Wait for the specified text to appear 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 wait_for? +

Register the Chrome Devtools MCP server in PolicyLayer and add a rule for wait_for: 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 wait_for? +

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

Can I rate-limit wait_for? +

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

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

wait_for is provided by the Chrome Devtools MCP server (shivamprasad99/chrome-devtools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.