key_down · macOS Control MCP Server MCP: Risk & Policy

WHAT IT DOES

What key_down does on macOS Control MCP Server

AI agents invoke key_down to trigger actions in macOS Control MCP Server. 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 key_down needs a policy

This tool simulates keyboard input by holding down a key on the system. It can trigger arbitrary keyboard shortcuts, modify system settings, or interact with any application. Combined with other tools in this server (hotkey, click_mouse, etc.), it enables full desktop automation that could be misused to execute commands, manipulate files, or control the OS.

From the tool's definition Hold down a key (must call key_up to release)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

key_down Rate-limited

key_down 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": {
    "key_down": {
      "limits": [
        {
          "counter": "key_down_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 macOS Control MCP Server, so you can run agents against it safely.

FAQ

Questions about key_down

What does the key_down tool do? +

Hold down a key (must call key_up to release). It is categorised as a Execute tool in the macOS Control MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on key_down? +

Register the macOS Control MCP Server MCP server in PolicyLayer and add a rule for key_down: 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 macOS Control MCP Server. Nothing to install.

What risk level is key_down? +

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

Can I rate-limit key_down? +

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

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

key_down is provided by the macOS Control MCP Server MCP server (lodimup/macos-control-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.