puppeteer_evaluate

THE RISK

High Risk

Why puppeteer_evaluate needs a policy

This tool executes arbitrary JavaScript in a browser context, which qualifies as Execute category. The severity is high because JavaScript execution can access sensitive data, manipulate DOM, exfiltrate information, trigger network requests, or perform actions on behalf of the user. The ability to execute arbitrary code without inherent restrictions creates significant blast radius for agent misuse.

From the tool's definition Tool name "puppeteer_evaluate" combined with description "Execute JavaScript in the browser console" indicates arbitrary code execution capability.

Documented attack patterns abuse exactly the kind of access puppeteer_evaluate gives an agent:

POLICY

How to control puppeteer_evaluate

PolicyLayer is an MCP gateway — it sits between your AI agents and MCP-Brave-Search, and nothing reaches the server without passing your rules. This is the rule we recommend for puppeteer_evaluate:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "puppeteer_evaluate": {
      "limits": [
        {
          "counter": "puppeteer_evaluate_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

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.

Create a free account and register MCP-Brave-Search — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

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Go deeper

High-risk tools in MCP-Brave-Search → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

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-Brave-Search 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-Brave-Search 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-Brave-Search. 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-Brave-Search MCP server (modelcontextprotocol/servers-archived). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP-Brave-Search tool call.

Start from MCP-Brave-Search, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →