press_key · JS Reverse MCP: Risk & Policy

WHAT IT DOES

What press_key does on JS Reverse MCP

AI agents invoke press_key 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 press_key needs a policy

This tool triggers browser actions (key presses) on an active page, which can cause side effects depending on the page context—submitting forms, triggering shortcuts, navigating, or interacting with application state. It falls under Execute as it performs external browser operations whose effects depend on arguments and context.

From the tool's definition Press a keyboard key on the active page

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

press_key Rate-limited

press_key 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": {
    "press_key": {
      "limits": [
        {
          "counter": "press_key_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 press_key

What does the press_key tool do? +

Press a keyboard key on the active page. 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 press_key? +

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

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

Can I rate-limit press_key? +

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

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

press_key is provided by the JS Reverse MCP server (noone-hub/jsreverser-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.