wait_for_ui · MacWright MCP: Risk & Policy

WHAT IT DOES

What wait_for_ui does on MacWright

AI agents invoke wait_for_ui 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 wait_for_ui needs a policy

This tool executes UI automation control logic on the macOS desktop. While it doesn't directly destructive or financial in nature, it triggers conditional execution flows that could cause unintended app behavior if misused. It's more severe than Read/Write because it actively manipulates application state and timing, but less severe than full script execution without UI monitoring.

From the tool's definition Tool performs UI automation by waiting for and triggering app state changes ('Wait for a native macOS UI element to appear in an app'), which is a control operation whose effects depend on runtime conditions and subsequent user-agent actions.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

wait_for_ui Rate-limited

wait_for_ui 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": {
    "wait_for_ui": {
      "limits": [
        {
          "counter": "wait_for_ui_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 wait_for_ui

What does the wait_for_ui tool do? +

Wait for a native macOS UI element to appear in an app. 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 wait_for_ui? +

Register the MacWright MCP server in PolicyLayer and add a rule for wait_for_ui: 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 wait_for_ui? +

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

Can I rate-limit wait_for_ui? +

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

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

wait_for_ui 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.