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

Annotations only supply readOnlyHint=true, so the description must carry the rest, and it does add real context: the default for overlays, an implied default resolution cap, and the fact that the file parameter writes a PNG to disk instead of returning it. It also discloses that region framing is interpreted in picture pixels by default, which affects results. The disk write slightly strains readOnlyHint, but it is opt-in and caller-specified, and the description is explicit about it rather than hiding it.

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?

Sentences are short, front-loaded with what the tool returns, then option behaviors, then the output location note. A few phrases are padded ('the picture with its lights, vents, parts and zone outlines') and the wording is telegraphic, but nothing is redundant at the sentence level.

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?

There is no output schema, so the description must partly explain the return value, and it does by describing pictureBox (x, y, pixels per picture pixel) and the file alternative. For a 6-parameter tool with a nested region object, defaults on overlays and maxWidth are the main things left to the schema, which is acceptable.

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 description coverage is 100%, so the parameters are already documented. The description mostly restates them (labels, region + zoom, file), adding only the qualifier that labels apply on interior pages and the note that pictureBox is reported in the answer. That is marginal added meaning, consistent with the baseline 3 when the schema does the heavy lifting.

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 first sentence names the resource concretely: a rendered picture of the page's screen, covering both the head-unit screen and the design picture with lights, vents, parts and zone outlines. It is distinctly a rendering/inspection tool, which separates it from data siblings like get_scene_data or get_state. It stops short of naming which sibling to use when the agent wants an existing asset instead of a fresh render (get_image, export_image, get_preview).

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?

Usage is only implied through option descriptions: 'labels ... (interior pages)', 'region + zoom shows a part up close', 'with file, the PNG is written there instead of shown'. These tell an agent how to get close-ups or annotated views, which is useful, but no sentence says when to choose this over get_image, get_preview or export_image, and there are no exclusions or prerequisites.

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