computer_screen_size

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

No annotations are provided, so the description carries the burden. It discloses that the tool returns a JSON envelope whose data carries the screen size, and that it requires a serialno from list_devices. It does not mention whether this is a read-only operation, but 'Get' implies it. It could add more context about units or coordinate system, but the core behavior is reasonably transparent.

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 compact and front-loaded: the first sentence states the purpose, the second gives the use case, and the Args/Returns sections are minimal and useful. Every sentence earns its place with no fluff.

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 has one required parameter, no annotations, and an output schema. The description explains the parameter source, the return envelope, and the intended use case. It could mention units or coordinate system details, but for a simple getter with one param, it is nearly complete.

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 0%, so the description must compensate. It explains that serialno is 'the computer device serialno, from list_devices,' which adds meaning beyond the schema's bare 'Serialno' title. However, it doesn't elaborate on how to obtain it beyond referencing list_devices, which is sufficient for a single 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 states a specific verb and resource: 'Get the primary screen size.' It also explains the purpose: converting coordinates returned by a vision model before calling computer_click. This clearly distinguishes it from sibling tools like computer_position or screenshot.

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 gives explicit context for when to use the tool: before calling computer_click, to convert vision-model coordinates. It does not explicitly name alternatives or exclusions, but the use case is clear enough for an agent to select it appropriately.

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