focus_ui_element · Mac MCP: Risk & Policy

WHAT IT DOES

What focus_ui_element does on Mac

AI agents invoke focus_ui_element to trigger actions in Mac. 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 focus_ui_element needs a policy

Focusing a UI element triggers an external UI interaction on the macOS system — it changes the active input target, which can affect subsequent keyboard input routing and application state. This goes beyond a passive read but is not a write/destructive action; it executes a UI automation action with side effects on the running system.

From the tool's definition Sets keyboard focus to a UI element

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

focus_ui_element Rate-limited

focus_ui_element 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": {
    "focus_ui_element": {
      "limits": [
        {
          "counter": "focus_ui_element_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 Mac, so you can run agents against it safely.

FAQ

Questions about focus_ui_element

What does the focus_ui_element tool do? +

Sets keyboard focus to a UI element. It is categorised as a Execute tool in the Mac MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on focus_ui_element? +

Register the Mac MCP server in PolicyLayer and add a rule for focus_ui_element: 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 Mac. Nothing to install.

What risk level is focus_ui_element? +

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

Can I rate-limit focus_ui_element? +

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

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

focus_ui_element is provided by the Mac MCP server (laststance/mac-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.