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

Annotations already establish that this is a read-only, non-destructive, closed-world operation, so the description is not burdened with safety disclosure. It usefully adds behavior beyond annotations: the data is scoped to the signed-in user's cloud library, OCR text is capped at 1,200 characters, and the image URL is temporary.

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 a single front-loaded sentence with a colon-separated list of key return elements. It is appropriately sized for a simple read-by-id tool and contains no filler.

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 one-parameter read tool with annotations and an output schema, this description is complete enough: it identifies the signed-in-user scope and summarizes the image, metadata/OCR, and temporary URL. Error cases are not described, but the structured fields and output schema cover the remaining contract.

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 single id parameter is already well documented as coming from list_screenshots or search_screenshots. The description adds no parameter-specific semantics beyond saying it shows one screenshot, so baseline 3 is appropriate.

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 gives a clear verb and resource: 'Show one screenshot' from the signed-in user's cloud library, and it specifies the return contents. It implicitly distinguishes retrieval from list/search/delete/rename by emphasizing a single screenshot, but it does not explicitly name sibling tools or contrast them.

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 does not say when to use this tool versus alternatives such as list_screenshots or search_screenshots, nor does it state when not to use it. The only routing hint is in the input schema's id field, not in the description itself.

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