screenshot

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

With no annotations provided, the description carries the behavioral disclosure burden. It states that the tool returns an image, shows the current UI state, and is meant for orientation, which implies a non-destructive read operation. It could add details about failure modes or image format, but nothing in the description misleads or hides critical behavior.

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 short sentences with no wasted words. The core action is front-loaded, the return value is stated immediately after, and the usage tip is a natural closing. Every sentence adds value.

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?

For a simple screenshot tool with no required parameters and no output schema, the description is reasonably complete: it states what is captured, what is returned, and when to call it. The remaining details, such as pid targeting behavior, are already covered by the schema. Minor omissions like error behavior keep it from a perfect score.

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 description adds meaning to the widget_id parameter by explaining it targets 'a specific widget by ID,' which the schema does not document. The pid parameter is already well-described in the schema, including its default behavior. Together, the description and schema provide sufficient semantic coverage for both parameters.

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 specific action ('Capture a screenshot'), the resource ('the app window' or 'a specific widget by ID'), and the return value ('the image'). This makes it easy to distinguish from sibling tools like get_widget_tree or get_widget_info, which serve different inspection purposes.

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 a clear usage directive: 'Call this first to orient yourself.' This tells the agent when to use the tool in the overall workflow. It does not explicitly discuss when not to use it or name alternative tools, but the guidance is sufficient for a straightforward screenshot tool.

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