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

With no annotations provided, the description carries the burden. It discloses the prerequisite of an active iOS automation session, which is useful. However, it does not mention the exact return format (whether width and height are included), or whether orientation changes affect the value, leaving gaps for an agent.

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 sentences with no fluff. The primary purpose is front-loaded, and the requirement of an active session is placed at the end as a necessary prerequisite. Every word serves a function.

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 simplicity (one parameter, no output schema), the description is adequate but not complete. It lacks details about the output format (e.g., does it return width only or a dict with width/height?) and any caveats like orientation changes, which an agent might need for accurate coordinate mapping.

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% (only 'udid'), and the description adds context that the UDID identifies the device whose screen width is retrieved. This supplements the schema's minimal 'iOS device UDID' with the purpose of the parameter.

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 clearly states the action ('Get the screen width'), the resource ('iOS device'), and the purpose ('Use these dimensions for tap/swipe coordinates'). It is distinct from sibling tools like ios_device_info and ios_swipe, indicating it returns dimensions for coordinate calculations.

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 clearly implies usage for tap/swipe coordinate determination and explicitly requires an active iOS automation session. However, it does not explicitly state when NOT to use it or name alternative tools, but given the uniqueness of 'screen width', the usage context is clear enough.

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