reveal_in_finder · Mac MCP: Risk & Policy

WHAT IT DOES

What reveal_in_finder does on Mac

AI agents invoke reveal_in_finder 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 reveal_in_finder needs a policy

This tool triggers an external application (Finder) and performs a UI action (revealing/selecting a file or folder). While it doesn't modify or delete data, it executes an operation that interacts with the macOS system and UI, making it Execute rather than Read. Misuse could expose sensitive file paths or locations to view.

From the tool's definition Opens Finder and selects the specified file or folder

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

reveal_in_finder Rate-limited

reveal_in_finder 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": {
    "reveal_in_finder": {
      "limits": [
        {
          "counter": "reveal_in_finder_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 reveal_in_finder

What does the reveal_in_finder tool do? +

Opens Finder and selects the specified file or folder. 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 reveal_in_finder? +

Register the Mac MCP server in PolicyLayer and add a rule for reveal_in_finder: 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 reveal_in_finder? +

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

Can I rate-limit reveal_in_finder? +

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

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

reveal_in_finder 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.