Get Screen Size

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

The annotation readOnlyHint=true already signals a safe read operation, and the description's 'Get' is consistent with that. The description adds minor value by specifying the unit 'pixels' and the device scope, but does not disclose the return format or any other behavioral details.

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?

A single, clear sentence delivers the essential information with no filler. The action and subject are front-loaded, making it immediately scannable.

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?

The tool is simple, but since there is no output schema, the description leaves ambiguity about the exact return structure (e.g., width x height vs. diagonal). The phrase 'in pixels' offers the unit but not the shape of the result, which is a notable gap.

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 fully documents the single 'device' parameter, including guidance to use mobile_list_available_devices. The description itself does not add parameter semantics beyond the schema, so the baseline score of 3 is appropriate.

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 verb 'Get' and the resource 'screen size' with an explicit unit ('in pixels'). This sufficiently distinguishes it from sibling tools like mobile_get_orientation, which retrieves a different device property.

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 provides no guidance on when to use this tool versus alternatives. The only contextual hint appears in the schema's parameter description (referencing mobile_list_available_devices), which helps with parameter selection but not tool selection.

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