start_app

THE RISK

High Risk

This tool triggers external operations (app launch) on an Android device with effects that depend on the arguments provided (which app package to launch). While launching a benign app poses low risk, the ability to programmatically launch arbitrary applications—including malicious ones, background services, or apps that trigger financial transactions—makes this an Execute category tool.

From the tool's definition Tool description states it will "Launch an Android application by its package name" - this is direct execution of operations on a device whose effects depend on which app is specified as an argument.

Documented attack patterns abuse exactly the kind of access start_app gives an agent:

HOW TO CONTROL START_APP

PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Android Agent, and nothing reaches the server without passing your rules. This is the rule we recommend for start_app:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "start_app": {
      "limits": [
        {
          "counter": "start_app_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

start_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.

Create a free account and register MCP Android Agent — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

More MCP Android Agent tools

Destructive clear_app_data Clear all data and cache for a specific app. This is equivalent to Execute stop_all_apps Force stop all running applications on the device to free up memory and start with a clean Execute stop_app Force stop an Android application by its package name. Useful for closing apps that are mi Execute wait_activity Wait for a specific Android activity to appear on the screen. Useful for navigation verifi Execute wait_for_element Wait for a UI element to appear on the screen. Essential for handling loading screens, ani Execute wait_for_screen_on Wait until the device screen is turned on. Useful for asynchronous operations where screen Execute click Click on a UI element identified by text, resource ID, or content description. Supports mu Execute connect_device Connect to an Android device using uiautomator2 and return comprehensive device informatio

All 28 MCP Android Agent tools →

Execute tools on other servers

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Go deeper

High-risk tools in MCP Android Agent → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

What does the start_app tool do? +

Launch an Android application by its package name with optional wait for the app to appear in foreground. It is categorised as a Execute tool in the MCP Android Agent MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_app? +

Register the MCP Android Agent MCP server in PolicyLayer and add a rule for start_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 MCP Android Agent. Nothing to install.

What risk level is start_app? +

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

Can I rate-limit start_app? +

Yes. Add a rate_limit block to the start_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 start_app completely? +

Set action: deny in the PolicyLayer policy for start_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 start_app? +

start_app is provided by the MCP Android Agent MCP server (nim444/mcp-android-server-python). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP Android Agent tool call.

Deterministic rules across all 28 MCP Android Agent tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.

GOVERN MCP ANDROID AGENT →

Free to start. No card required.

28 MCP Android Agent tools catalogued and risk-classified — across an index of 42,500+ MCP servers.

// WHAT START_APP ON MCP ANDROID AGENT DOES

// THE RISK

// HOW TO CONTROL START_APP

// EXPLORE