focus_window · MacWright MCP: Risk & Policy

WHAT IT DOES

What focus_window does on MacWright

AI agents invoke focus_window to trigger actions in MacWright. 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_window needs a policy

Focusing a window triggers an external UI operation that changes the active application/window state on the desktop. This is not a pure read operation, nor does it create/modify data—it's an OS-level action that affects application focus. The description is truncated/uninformative, slightly lowering confidence, but the name and partial description clearly indicate a desktop control action.

From the tool's definition 'focus_window' - 'Bring a specific application'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

focus_window Rate-limited

focus_window 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_window": {
      "limits": [
        {
          "counter": "focus_window_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 MacWright, so you can run agents against it safely.

FAQ

Questions about focus_window

What does the focus_window tool do? +

Bring a specific application. It is categorised as a Execute tool in the MacWright 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_window? +

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

What risk level is focus_window? +

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

Can I rate-limit focus_window? +

Yes. Add a rate_limit block to the focus_window 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_window completely? +

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

focus_window is provided by the MacWright MCP server (ruchit-p/macwright). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.