adb-mcp

ADB MCP Tools

The android-debug-bridge MCP server exposes an Android device to the agent as tools. Every device-facing tool takes an optional device argument — a full serial, a serial prefix, a transport id or a model name — and defaults to ADB_SERIAL or the only connected device.

The same engine is available as the adb-agent CLI — see the adb-cli skill. Reach for the CLI when a flow is a straight sequence of steps you want to chain in one shell call; reach for these tools when you want images in the transcript and per-step reasoning.

Before the first action

Call list_devices. If it comes back empty, tell the user to start an emulator or connect a device with USB debugging enabled — do not keep trying other tools, they will all fail the same way. If it lists more than one device, the result says whether there is a default target; when there is none, pick one and pass device on every later call rather than letting each tool fail in turn.

Then call device_info once. Screen size, Android version and emulator status shape everything after it: which coordinates are valid, whether a permission model applies, whether a hardware key exists.

The core loop

Read, act, verify:

1. capture_ui_dump or ui_find to see what is on screen.
2. ui_tap with a label, not input_tap with a guess.
3. ui_wait_for before touching the next screen, then repeat.

ui_tap re-reads the tree, ranks matches on text, content-description and resource-id, prefers clickable and enabled elements, and taps the best one. Fixed coordinates break on a different device; labels usually do not.

ui_tap also refuses to tap through an overlay. The tree reports full logical bounds with no notion of what is painted on top, so a banner under a bottom bar still claims those pixels — tapping its center fires the bar and reports success for the wrong element. The tool looks for an uncovered point inside the element first, and errors with the name of the blocker when there is none. Pass force: true to override once you know what is on top.