Presses a hardware button on a USB-connected iPhone or iPad—Home, volume up, or volume down—to control device navigation and audio during app testing.
Press a hardware button. "home" goes to the home screen.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | ||
| device | No | Device UDID or name substring. Defaults to the select_device choice, then IOS_DEVICE_MCP_DEVICE, else the single USB-connected device. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden and only discloses that 'home' navigates to the home screen. It says nothing about what volumeUp/volumeDown do, whether a driver/session must be active, whether the action is reversible, or what errors occur for unsupported buttons.
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?
Two short sentences, front-loaded with the core action, and the second sentence adds useful behavioral context. It is efficient, though the terseness borders on under-specification rather than pure conciseness.
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 device-control tool with no annotations and no output schema, the description is thin: it omits volume-button semantics, session/driver prerequisites, and any indication of success or failure behavior. The schema's device default helps, but the tool's overall contract is not sufficiently described.
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?
Schema coverage is only 50%, and the description compensates for just one of the three enum values ('home'). The volumeUp and volumeDown enum values remain undocumented, and the description adds nothing about the 'device' parameter beyond the schema's own substring/default explanation.
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 and resource ('Press a hardware button'), which distinguishes it from screen-level siblings like tap and tap_element. However, it only explains the 'home' value and never mentions that volumeUp and volumeDown are also valid targets, so the purpose is clear but incompletely framed.
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?
There is no explicit guidance on when to use this versus alternatives such as tap, tap_element, or set_volume, despite obvious overlap with set_volume for volume changes. The hardware-button framing implies usage but gives no exclusions or conditions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.