press_key

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations are absent, so the description must carry the behavioral disclosure burden, yet it only lists valid keys. It does not mention side effects (e.g., power toggling screen state), whether the press is a discrete tap-and-release, or that a connected device is required. For a state-changing action, this is a meaningful transparency gap.

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?

The description is a single, well-structured sentence with no filler. The verb is front-loaded, and every listed key is necessary given the one-parameter schema.

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 one-parameter tool with an output schema, the description is usable out of the box. However, it omits behavioral context such as device connection requirements and side effects, and it offers no guidance on when to use this instead of sibling input tools. It is adequate but not rich.

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 input schema gives no parameter description (0% coverage), but the description compensates by listing the permitted keys in prose and clarifying 'recent' as the app switcher. However, the schema's enum already communicates the allowed values, so the added semantic value is modest.

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?

The description opens with a specific verb and resource ('Press a device key') and enumerates the exact supported keys, making its scope immediately clear. It naturally distinguishes itself from gesture-based siblings like tap, double_tap, and long_press.

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?

The description implies when to use the tool—whenever a device key needs to be pressed—but it does not explicitly state when not to use it or how it compares to alternatives such as tap or input_text. The key list provides indirect differentiation, but no direct routing guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.