select_frame · JS Reverse MCP: Risk & Policy

WHAT IT DOES

What select_frame does on JS Reverse MCP

AI agents use select_frame to create or update resources in JS Reverse MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your JS Reverse MCP environment.

WHY IT NEEDS A POLICY

Why select_frame needs a policy

An AI agent can call select_frame faster than any human can review — one bad instruction and it creates or modifies resources in JS Reverse MCP by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

select_frame Rate-limited

select_frame stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "select_frame": {
      "limits": [
        {
          "counter": "select_frame_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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 select_frame

What does the select_frame tool do? +

Lists all frames (including iframes) in the current page. Pass frameIdx to switch the execution context used by evaluate_script. Other tools may still operate at page level. It is categorised as a Write tool in the JS Reverse MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on select_frame? +

Register the JS Reverse MCP server in PolicyLayer and add a rule for select_frame: 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 select_frame? +

select_frame is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit select_frame? +

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

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

select_frame 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.