wm_size

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

With no annotations, the description carries the full burden. It discloses that the operation is read-only through 'Returns' and implicitly indicates no side effects. It does not, however, describe the return format, units, or what happens if no device is connected.

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 two short sentences with no filler. The core purpose is front-loaded, and stating that no parameters are required is a useful clarification with zero waste.

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 zero-parameter read-only query tool this is nearly complete: an agent knows what the tool returns and how to invoke it. The only minor gap is not specifying the expected format of the screen size, but the low complexity and empty schema keep it sufficient.

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 is empty and the description reinforces that no parameters are required. Since there are zero parameters, the baseline is 4, and the description fully satisfies the need without adding unnecessary detail.

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 states a specific verb ('Returns'), a specific resource ('screen size of the connected Android device'), and defines the scope (screen size specifically, not density or other device properties). This clearly distinguishes it from siblings like wm_density and get_properties.

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 makes the invocation trivially clear by stating 'No parameters are required.' However, it does not explain when to prefer this tool over related device-info siblings, nor mention any alternatives or exclusion cases.

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