Get Screen Size

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

Annotations already indicate readOnlyHint=true, so the agent knows this is a safe read operation. The description adds no further behavioral context, such as what the return format is (e.g., width x height) or if any side effects occur. Given the annotation, a score of 3 is appropriate as the description doesn't contradict but also doesn't add value.

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 of 11 words that directly states the purpose. No fluff, no repetition. It is concise and front-loaded.

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 mostly complete. However, it could mention that the return value is width and height in pixels to avoid ambiguity. Still, for a basic getter, this is 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 covers the only parameter 'device' with a description that tells the user to use mobile_list_available_devices to find valid identifiers. Since schema description coverage is 100%, the description doesn't need to add more. It adds marginal 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 clearly states the tool's purpose: retrieving the screen size of a mobile device in pixels. It uses a specific verb ('Get') and resource ('screen size'), and it distinguishes itself from sibling tools that perform actions like clicking, swiping, or getting orientation.

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. For instance, it doesn't mention that this tool might be a prerequisite for coordinate-based actions, nor does it explain when not to use it. There is no explicit context or exclusion.

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