os_voiceover_stop · OScribe MCP: Risk & Policy

WHAT IT DOES

What os_voiceover_stop does on OScribe

AI agents invoke os_voiceover_stop to trigger actions in OScribe. 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 os_voiceover_stop needs a policy

This tool triggers external operation (stopping a system service) whose effects depend on system state. While not destructive (service can be restarted), stopping accessibility features could disable critical user-assistance tools and affect system usability. Categorized as Execute rather than Read or Write because it performs an action with side effects on the operating system.

From the tool's definition Tool name 'os_voiceover_stop' and description 'Stop VoiceOver screen reader' indicate execution of system-level control—terminating a running accessibility service on macOS.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

os_voiceover_stop Rate-limited

os_voiceover_stop 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": {
    "os_voiceover_stop": {
      "limits": [
        {
          "counter": "os_voiceover_stop_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 OScribe, so you can run agents against it safely.

FAQ

Questions about os_voiceover_stop

What does the os_voiceover_stop tool do? +

Stop VoiceOver screen reader. macOS only. It is categorised as a Execute tool in the OScribe MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on os_voiceover_stop? +

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

What risk level is os_voiceover_stop? +

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

Can I rate-limit os_voiceover_stop? +

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

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

os_voiceover_stop is provided by the OScribe MCP server (mikealkeal/oscribe). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.