screenshot_cropped

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

No annotations are provided, so the description carries the full burden. It adds useful behavioral details: 'Coordinates are in device pixels' and 'Returns base64-encoded JPEG.' However, it omits coordinate origin/order (top-left vs bottom-right), bounds validation, and implications for the 'device' parameter, leaving some behavioral gaps.

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 three sentences with no fluff: action, coordinate system, use case, and return format. It is front-loaded with the main purpose and each sentence adds value. The parenthetical examples make the use case concrete without wasting space.

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 and the presence of an output schema, the description covers the core need: what it does, when to use it, coordinate units, and return format. However, it is not fully complete because it leaves the 'device' parameter undefined and does not clarify how the coordinate pair defines the region, which could lead to incorrect invocation.

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 coverage is 0%, so the description must compensate. It explains that coordinates are in device pixels, giving some meaning to x1/y1/x2/y2, but it does not define what the coordinate pairs represent (e.g., top-left and bottom-right corners) and does not explain the 'device' parameter at all. This is a significant gap for a 5-parameter tool.

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: 'Take a screenshot of a specific region of the screen.' This specific verb+resource phrasing distinguishes it from siblings like 'screenshot' (full screen) and 'screenshot_annotated' (annotated) by emphasizing the cropped region and 'zoom in' use case.

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 clear context for when to use this tool: 'Use this to zoom in on a specific area (e.g., a form field, a notification, a chart).' It does not explicitly mention alternatives or when not to use it, but the guidance is sufficient for a focused screenshot tool.

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