# AndroidBackButton

AndroidBackButton action, Trigger the system "back" operation on Android devices

Agent View of the PolicyLayer registry record for `AndroidBackButton`. HTML page: https://policylayer.com/tools/android/androidbackbutton

## Facts

- Tool: `AndroidBackButton`
- Server: Android (`@midscene/android-mcp`) — https://policylayer.com/tools/android.md
- Install: `npx -y @midscene/android-mcp`
- Homepage: https://www.npmjs.com/package/@midscene/android-mcp
- Risk category: Execute (High risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 6
- Recommended policy verdict: Rate-limited

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `android.deviceId` | string | no | Android device ID (from adb devices) |
| `android.useScrcpy` | boolean | no | Enable scrcpy accelerated screenshots |
| `android.aiActContext` | string | no | Background knowledge passed to aiAct. Default: no extra context. |
| `android.waitAfterAction` | number | no | Wait time in milliseconds after each action execution. Default: 300ms. |
| `android.replanningCycleLimit` | integer | no | Maximum number of replanning cycles for aiAct. Default: model adapter default. |
| `android.screenshotShrinkFactor` | number | no | Screenshot shrink factor before sending images to AI. Default: 1; high values may reduce recognition quality, especially on mobile. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "AndroidBackButton",
    "arguments": {}
  }
}
```

## Why AndroidBackButton is rated High

This tool executes a system command on an Android device (simulating a back button press), which triggers real device behavior. While the action itself is reversible and not destructive, it falls into the Execute category because it runs an external operation whose effects depend on the current app/system state and context.

From the tool's own definition: "Tool description states it will 'Trigger the system back operation on Android devices' - this executes a device-level action with external side effects."

## Use case

AI agents invoke AndroidBackButton to trigger actions in Android. 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.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Android:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "AndroidBackButton": {
      "limits": [
        {
          "counter": "androidbackbutton_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Android (22)

- `ClearInput` — Destructive — https://policylayer.com/tools/android/clearinput.md
- `act` — Execute — https://policylayer.com/tools/android/act.md
- `android_connect` — Execute — https://policylayer.com/tools/android/android-connect.md
- `AndroidHomeButton` — Execute — https://policylayer.com/tools/android/androidhomebutton.md
- `AndroidRecentAppsButton` — Execute — https://policylayer.com/tools/android/androidrecentappsbutton.md
- `CursorMove` — Execute — https://policylayer.com/tools/android/cursormove.md
- `DoubleClick` — Execute — https://policylayer.com/tools/android/doubleclick.md
- `DragAndDrop` — Execute — https://policylayer.com/tools/android/draganddrop.md
- `KeyboardPress` — Execute — https://policylayer.com/tools/android/keyboardpress.md
- `Launch` — Execute — https://policylayer.com/tools/android/launch.md
- `LongPress` — Execute — https://policylayer.com/tools/android/longpress.md
- `Pinch` — Execute — https://policylayer.com/tools/android/pinch.md
- `PullGesture` — Execute — https://policylayer.com/tools/android/pullgesture.md
- `RunAdbShell` — Execute — https://policylayer.com/tools/android/runadbshell.md
- `Scroll` — Execute — https://policylayer.com/tools/android/scroll.md
- `Swipe` — Execute — https://policylayer.com/tools/android/swipe.md
- `Tap` — Execute — https://policylayer.com/tools/android/tap.md
- `Terminate` — Execute — https://policylayer.com/tools/android/terminate.md
- `take_screenshot` — Read — https://policylayer.com/tools/android/take-screenshot.md
- `android_disconnect` — Write — https://policylayer.com/tools/android/android-disconnect.md
- `assert` — Write — https://policylayer.com/tools/android/assert.md
- `Input` — Write — https://policylayer.com/tools/android/input.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=android · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/android