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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds genuinely non-structured behavior: the capture is viewport-limited ("visible part") and returns JPEG, and image coordinates can be reused as click/drag targets. It does not mention whether scrolling is needed for off-screen content, but the viewport framing implies that.

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?

Two short sentences, the output format is front-loaded, and every clause carries actionable information (what you get, when to use it, how to act on it). Nothing is redundant with the title or annotations.

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 one-optional-parameter read-only tool with no output schema, the description covers format, scope, and intended next action, which is enough to invoke it correctly. A note about scrolling for content outside the viewport would close the remaining gap.

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?

There is a single optional `app` parameter and schema description coverage is 100%, with the schema itself explaining the 'leave it out' default and the Cloud Browser exception. The description says nothing about the parameter, so it adds no meaning beyond the schema — the baseline 3 for high coverage applies.

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 names the concrete output ("A JPEG of the visible part of the page"), which tells an agent exactly what the tool produces, and it implicitly separates itself from cotlet_browser_read by covering content "the text does not show". It stops short of naming that sibling, so the differentiation is inferred rather than explicit.

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?

It gives a clear use condition — visual artifacts such as boards, canvases, maps, charts and layout — and then describes the follow-up action an agent should take with the result (click or drag by image x/y). The missing piece is an explicit exclusion pointing to cotlet_browser_read when the content is textual.

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