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

Annotations already cover read-only and closed-world, so the description earns credit for adding what they do not: sign-in is required, results are newest-first, previews cap the page at 12, and re-downloading via fulfil_image is free. Pagination mechanics via cursor are left unexplained.

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?

Three short sentences, each carrying distinct information: scope and ordering, the fulfil_image cost relationship, and the preview mode plus auth requirement. Nothing is repeated from annotations or schema, and the key scoping fact is front-loaded.

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?

An output schema exists, so return shape need not be described, and the auth requirement plus the preview-mode cost tradeoff are covered. The missing piece is a word on how cursor/limit paging behaves, which matters for a bounded list endpoint.

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 coverage is 33%. include_previews is well explained beyond its schema description (no per-image fulfil_image call, page capped at 12), but limit and cursor have neither schema descriptions nor any mention here, so half the parameters remain opaque.

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?

States the resource and scope precisely: everything the signed-in buyer has bought, ordered newest first. That scope implicitly separates it from search_images (which browses) and list_collections. The verb is only implied by the name rather than stated, which keeps it short of a 5.

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?

Gives an explicit condition for the main mode switch ('Pass include_previews: true whenever the person wants to see their library') and routes the re-download case to fulfil_image. It does not contrast itself against search_images or list_collections, so the alternative guidance is partial rather than complete.

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