AI agents call app_clear to permanently remove resources in uiautomator2 MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
The 'app_clear' tool most likely clears application data, cache, or uninstalls apps on a controlled Android device. These are destructive operations that cannot be undone and result in permanent data loss. Even if it only clears cache (less severe), the sibling context of app management tools (app_install, app_stop, app_start) and the automation nature suggest this has destructive potential.
From the tool's definition Tool named 'app_clear' with context of Android device management via uiautomator2. The name 'clear' in Android typically refers to clearing app cache, app data, or uninstalling applications—operations that destroy user data irreversibly.
Documented attack patterns abuse exactly the kind of access app_clear 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_clear:
{
"version": "1",
"default": "deny",
"hide": [
"app_clear"
]
}app_clear disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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app_clear. It is categorised as a Destructive tool in the uiautomator2 MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the uiautomator2 MCP Server MCP server in PolicyLayer and add a rule for app_clear: 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_clear is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the app_clear 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_clear. 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_clear 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.
Free to start. No card required.
77 uiautomator2 MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.