page_prepare · MCP Playwright Server MCP: Risk & Policy

WHAT IT DOES

What page_prepare does on MCP Playwright Server

AI agents invoke page_prepare to trigger actions in MCP Playwright Server. 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 page_prepare needs a policy

This tool modifies browser page configuration including sensitive settings like geolocation and permissions. It triggers external browser operations with side effects that affect subsequent interactions. While not destructive or financial, it executes browser-level configuration changes that can influence behavior of a live browser session, placing it in the Execute category.

From the tool's definition Configure page settings for testing (viewport, geolocation, permissions, color scheme, etc.)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

page_prepare Rate-limited

page_prepare 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": {
    "page_prepare": {
      "limits": [
        {
          "counter": "page_prepare_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 Playwright Server, so you can run agents against it safely.

FAQ

Questions about page_prepare

What does the page_prepare tool do? +

Configure page settings for testing (viewport, geolocation, permissions, color scheme, etc.). It is categorised as a Execute tool in the MCP Playwright Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on page_prepare? +

Register the MCP Playwright Server MCP server in PolicyLayer and add a rule for page_prepare: 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 Playwright Server. Nothing to install.

What risk level is page_prepare? +

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

Can I rate-limit page_prepare? +

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

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

page_prepare is provided by the MCP Playwright Server MCP server (j0hanz/playwright-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.