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

WHAT IT DOES

What launch_app does on Expo Dev Build MCP Server

AI agents invoke launch_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 launch_app needs a policy

This is an Execute tool because it runs/triggers an operation (app launch) on a physical device with consequences that depend on the supplied argument (bundle ID). It is not Write (does not create/modify data reversibly), not Destructive (launching an app is reversible), and not Financial.

From the tool's definition The tool 'launch_app' launches an application on an iOS device by bundle ID. This triggers external operations (app execution) whose effects depend on the argument (which app to launch). Launching an app can have side effects depending on what the app does.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

launch_app Rate-limited

launch_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": {
    "launch_app": {
      "limits": [
        {
          "counter": "launch_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 launch_app

What does the launch_app tool do? +

Launch an application on the iOS device by its bundle ID. 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 launch_app? +

Register the Expo Dev Build MCP Server MCP server in PolicyLayer and add a rule for launch_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 launch_app? +

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

Can I rate-limit launch_app? +

Yes. Add a rate_limit block to the launch_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 launch_app completely? +

Set action: deny in the PolicyLayer policy for launch_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 launch_app? +

launch_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.