tap_element · Rn Debug MCP: Risk & Policy

WHAT IT DOES

What tap_element does on Rn Debug

AI agents invoke tap_element to trigger actions in Rn Debug. 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 tap_element needs a policy

This tool triggers a UI interaction (tap/click) on a mobile app element, which constitutes executing an action in an external application. The effect depends on what element is tapped and could trigger any in-app behavior, making it Execute category. Severity is medium as it can trigger arbitrary in-app actions but is constrained to visible UI elements.

From the tool's definition Tap a visible element by element id... Preferred fallback before coordinate tapping

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

tap_element Rate-limited

tap_element 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": {
    "tap_element": {
      "limits": [
        {
          "counter": "tap_element_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 Rn Debug, so you can run agents against it safely.

FAQ

Questions about tap_element

What does the tap_element tool do? +

Tap a visible element by element id from get_visible_elements/get_ui_tree. Preferred fallback before coordinate tapping. It is categorised as a Execute tool in the Rn Debug MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on tap_element? +

Register the Rn Debug MCP server in PolicyLayer and add a rule for tap_element: 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 Rn Debug. Nothing to install.

What risk level is tap_element? +

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

Can I rate-limit tap_element? +

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

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

tap_element is provided by the Rn Debug MCP server (rn-debug-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.