puppeteer_evaluate · MCP-pptr MCP: Risk & Policy

WHAT IT DOES

What puppeteer_evaluate does on MCP-pptr

AI agents invoke puppeteer_evaluate to trigger actions in MCP-pptr. 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 puppeteer_evaluate needs a policy

This tool allows execution of arbitrary JavaScript code within a browser environment. An AI agent with access to this tool can execute any JavaScript, including stealing cookies/session tokens, reading sensitive page content, performing unauthorized transactions, redirecting users, injecting malicious scripts, or exfiltrating data.

From the tool's definition Execute JavaScript in the browser console — directly executes arbitrary code in a browser context.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

puppeteer_evaluate Rate-limited

puppeteer_evaluate 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": {
    "puppeteer_evaluate": {
      "limits": [
        {
          "counter": "puppeteer_evaluate_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-pptr, so you can run agents against it safely.

FAQ

Questions about puppeteer_evaluate

What does the puppeteer_evaluate tool do? +

Execute JavaScript in the browser console. It is categorised as a Execute tool in the MCP-pptr MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on puppeteer_evaluate? +

Register the MCP-pptr MCP server in PolicyLayer and add a rule for puppeteer_evaluate: 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-pptr. Nothing to install.

What risk level is puppeteer_evaluate? +

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

Can I rate-limit puppeteer_evaluate? +

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

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

puppeteer_evaluate is provided by the MCP-pptr MCP server (ringotc/mcp-pptr). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.