phone_homePress the Android HOME button on a connected emulator or USB device to return to the home screen, then optionally re-inspect the UI and capture a screenshot.
Press HOME (convenience wrapper around phone_key).
| Name | Required | Description | Default |
|---|---|---|---|
| observe | No | Re-dump the UI after the action (default true) | |
| settleMs | No | Wait before re-observing, milliseconds | |
| includeScreenshot | No | Include a PNG screenshot in the response |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden, and it is a single clause. It does not say the device state changes (navigating to the home screen), whether the action is safe/idempotent, or what the call returns.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
One short, front-loaded sentence with zero filler; the action comes first and the clarifying note follows in parentheses.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple zero-required-parameter action with fully documented schema and no output schema, the description is minimally sufficient. It leaves thin gaps around device-state effect and why the wrapper exists, but nothing blocks correct invocation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The description mentions no parameters, but schema coverage is 100% with clear descriptions for observe, settleMs, and includeScreenshot. Baseline 3 applies when the schema fully documents the parameters.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb+resource ("Press HOME") and clarifies its relationship to the sibling phone_key as a convenience wrapper, which helps distinguish it. It does not, however, say how it differs from simply calling phone_key with a HOME keycode.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
By naming phone_key as the underlying operation, it implies this is a shortcut alternative, but it never states when to prefer this over phone_key directly or on which platforms/devices it applies. Usage is implied rather than specified.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.