screenshot

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

The description adds behavioral details beyond annotations: it activates tab in background without stealing focus, restores previous tab, and downscales to ≤1568px. Annotations already indicate read-only, idempotent, non-destructive, so no contradiction.

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 extremely concise with three short segments, front-loaded with the core purpose. Every sentence adds unique value without redundancy.

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 is simple with two optional params and no output schema. The description covers purpose, behavioral constraints, and side effects. It could mention the return format explicitly, but overall it is sufficient for correct agent 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?

With 100% schema description coverage, the baseline is 3. The description does not add significant meaning beyond the schema's descriptions for tab_id and save_to; it mainly provides context about the output (PNG) and constraints (downscaling) which are not parameter-specific.

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 specifies the tool captures a screenshot of the visible viewport as a PNG at the current scroll position. It distinguishes itself from sibling tools like element_screenshot and full_page_screenshot by explicitly stating 'viewport only' and 'current scroll position'.

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 tells when to use (viewport screenshot) and mentions behaviors like background tab activation and downscaling. It does not explicitly state when not to use or compare with alternatives, but the context of sibling tools and the specific constraints provide adequate guidance.

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