webview_tap · React Native MCP: Risk & Policy

WHAT IT DOES

What webview_tap does on React Native

AI agents invoke webview_tap to trigger actions in React Native. 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 webview_tap needs a policy

This tool executes a native tap action on a device via idb (iOS) or adb (Android), resolving CSS selectors to screen coordinates and performing real device input. It triggers external operations on the device whose effects depend on the element being tapped (could navigate, submit forms, trigger actions, etc.).

From the tool's definition 'Tap a DOM element inside a WebView using native tap... taps via idb/adb'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

webview_tap Rate-limited

webview_tap 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": {
    "webview_tap": {
      "limits": [
        {
          "counter": "webview_tap_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 React Native, so you can run agents against it safely.

FAQ

Questions about webview_tap

What does the webview_tap tool do? +

Tap a DOM element inside a WebView using native tap. Resolves CSS selector to screen coordinates via getBoundingClientRect + WebView native position, then taps via idb/adb. Use this when you need a real native tap on WebView content (e.g. for elements that don. It is categorised as a Execute tool in the React Native MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on webview_tap? +

Register the React Native MCP server in PolicyLayer and add a rule for webview_tap: 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 React Native. Nothing to install.

What risk level is webview_tap? +

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

Can I rate-limit webview_tap? +

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

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

webview_tap is provided by the React Native MCP server (@ohah/react-native-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.