AI agents invoke app_install to trigger actions in uiautomator2 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.
Installing an app on an Android device is an external operation with significant side effects — it places new executable code on the device, grants permissions, and can alter device behavior. While not purely destructive or financial, it triggers an external operation (APK installation) whose effects depend on the app being installed.
From the tool's definition Tool name 'app_install' on a server that controls Android devices via uiautomator2. Description is empty.
Documented attack patterns abuse exactly the kind of access app_install gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and uiautomator2 MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for app_install:
{
"version": "1",
"default": "deny",
"tools": {
"app_install": {
"limits": [
{
"counter": "app_install_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}app_install 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.
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app_install. It is categorised as a Execute tool in the uiautomator2 MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the uiautomator2 MCP Server MCP server in PolicyLayer and add a rule for app_install: 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 uiautomator2 MCP Server. Nothing to install.
app_install is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the app_install 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.
Set action: deny in the PolicyLayer policy for app_install. 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.
app_install is provided by the uiautomator2 MCP Server MCP server (tanbro/uiautomator2-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from uiautomator2 MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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77 uiautomator2 MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.