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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds ordering (newest first), return payload contents (public URLs, storage paths, byte sizes), and a conflict-behavior warning about concurrent edits in the editor. Most of that warning concerns the sibling write tools rather than this tool itself, which keeps it just short of a 5.

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 lead sentence front-loads purpose and return shape, and the two-use framing follows immediately. The second paragraph is slightly long and spends more words on sibling-tool hazards than on this tool, but every sentence carries actionable information.

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?

No output schema exists, and the description compensates by naming the returned fields. For a three-parameter read tool with full annotation coverage, an agent has everything needed to select and call it correctly.

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 100%, so site_id, limit, and since are already fully documented, establishing a baseline of 3. The description adds a workflow-level interpretation of `since` (pass the moment you sent the editor link), but no format or edge-case detail beyond the schema.

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?

Opens with a specific verb and resource ("List the images in a site's library, newest first, with their public URLs") and distinguishes itself from the upload-side siblings (upload_image, find_images, replace_images_from_search) by describing a read of the existing library. An agent knows exactly what it gets back without opening the schema.

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?

Names two concrete situations to use it (collecting what arrived after get_editor_link, and checking pre-existing images before upload) and pairs each with the follow-up tool. It goes further and states which downstream tools NOT to use (patch_fixture, replace_site) and why, which is real routing guidance rather than implied usage.

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