kill_app · Expo Dev Build MCP Server MCP: Risk & Policy

WHAT IT DOES

What kill_app does on Expo Dev Build MCP Server

AI agents invoke kill_app to trigger actions in Expo Dev Build MCP Server. 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 kill_app needs a policy

Force-quitting an app is an external operation that terminates a running process on a physical device. It is reversible (the app can be relaunched), so it does not qualify as Destructive, but it does trigger a significant external side effect (process termination) that goes beyond a simple write. Execute is the most appropriate category. Misuse could disrupt active user sessions or ongoing operations on the device.

From the tool's definition Force quit an application on the iOS device

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

kill_app Rate-limited

kill_app 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": {
    "kill_app": {
      "limits": [
        {
          "counter": "kill_app_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 Expo Dev Build MCP Server, so you can run agents against it safely.

FAQ

Questions about kill_app

What does the kill_app tool do? +

Force quit an application on the iOS device. It is categorised as a Execute tool in the Expo Dev Build MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on kill_app? +

Register the Expo Dev Build MCP Server MCP server in PolicyLayer and add a rule for kill_app: 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 Expo Dev Build MCP Server. Nothing to install.

What risk level is kill_app? +

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

Can I rate-limit kill_app? +

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

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

kill_app is provided by the Expo Dev Build MCP Server MCP server (ryan-crabbe/expo-dev-build-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.