press_key

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

No annotations are present, so the description carries the full burden. It transparently states the core action (pressing a hardware/software key), but it does not disclose side effects, whether the press targets the foreground app, or how it behaves with device_id omitted. Still, it is not misleading and gives the basic behavioral intent.

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 sentence with no wasted words, front-loads the action, and uses examples efficiently. It is appropriately sized for a simple input tool.

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?

Given the tool's low complexity, the schema fully documents both parameters, and there is no output schema requiring return-value explanation, this description is largely complete. The main gap is the lack of sibling differentiation for when to use this tool.

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 description coverage is 100%, so the input schema already documents the key and device_id parameters. The description adds only the generic 'hardware/software key' framing and examples, which adds minimal value beyond the schema.

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 uses a specific verb ('Press') and a clear resource ('hardware/software key') with concrete examples like BACK and HOME. It is not a tautology and is clearly separable from coordinate or element-based sibling tools, though it does not explicitly name those siblings.

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?

No guidance is given about when to use press_key versus alternatives such as long_press, tap_xy, or tap_element. The description implies key-based input but provides no exclusions, prerequisites, or context for selecting this tool.

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