new_page · JS Reverse MCP: Risk & Policy

WHAT IT DOES

What new_page does on JS Reverse MCP

AI agents invoke new_page to trigger actions in JS Reverse MCP. 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 new_page needs a policy

This tool executes browser navigation and page loading operations whose effects (executing page scripts, loading resources, triggering network requests, running third-party code) depend entirely on the URL provided. While not destructive or financial in nature, it is Execute-category because it performs active operations that modify browser state and trigger code execution on remote servers.

From the tool's definition Tool description states it 'Opens a browser page and navigates to the specified URL' and 'Waits for DOMContentLoaded event', which are browser automation actions that trigger external operations with side effects depending on the URL argument.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

new_page Rate-limited

new_page 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": {
    "new_page": {
      "limits": [
        {
          "counter": "new_page_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 JS Reverse MCP, so you can run agents against it safely.

FAQ

Questions about new_page

What does the new_page tool do? +

Opens a browser page and navigates to the specified URL. If an existing about:blank startup tab is still available, it is reused instead of opening an extra tab. Waits for DOMContentLoaded event (not full page load). Default timeout is 10 seconds. It is categorised as a Execute tool in the JS Reverse MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on new_page? +

Register the JS Reverse MCP server in PolicyLayer and add a rule for new_page: 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 JS Reverse MCP. Nothing to install.

What risk level is new_page? +

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

Can I rate-limit new_page? +

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

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

new_page is provided by the JS Reverse MCP server (zhizhuodemao/js-reverse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.