screenshot

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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It implies a read-only operation (capturing an image) but does not explicitly state safety, side effects, or limitations such as screen resolution or multi-monitor behavior. The description adds context about the return type but omits potential caveats.

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 only two sentences and every word earns its place. It prioritizes the core action first and then provides timely usage guidance, with no fluff or repetition.

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 zero-parameter tool with no output schema, the description covers the essential points: what it does, when to use it, and why it matters for other tools. It could mention whether it captures the entire desktop or the primary monitor, but the core usage is well covered given the tool's simplicity.

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 tool accepts no parameters, and the input schema confirms this. Since there are no parameters to document, the description correctly says nothing about them, and the baseline for zero-parameter tools is high.

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 action ('Capture the desktop') and the resulting output ('return it as an image'). It clearly distinguishes itself from sibling tools like click, move, and type_text, which all operate on coordinates relative to this image.

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?

Explicitly instructs when to take a screenshot: 'before acting' and 'after any action whose result you need to see.' It also tells agents why this matters by noting that 'all other tools expect coordinates measured on this image,' which connects to how the tool should be used in the workflow.

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