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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so safety is covered. The description adds the genuinely useful fact that results carry a uid consumed by create_post, but stays silent on pagination (page/limit exist) and on the fact that document/audio items cannot be attached despite being listable.

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 sentences, zero filler, with the core capability stated first and the downstream usage second. Nothing could be removed without losing 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?

For a read-only list tool with annotations covering safety, this is nearly complete: it names the resource, the scope, and the shape of at least one returned field (uid), which matters because there is no output schema. Missing only pagination guidance and the type-vs-attachability caveat.

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 60%, so the description is not obligated to carry everything, yet 'images/videos' reinforces the type filter's practical meaning and the uid hint connects results to a parameter. It still leaves page and limit unexplained in either place, so it does not fully compensate for the coverage gap.

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 a specific verb and resource ('List images/videos in the user's Feedlio media library'), which cleanly separates it from siblings like add_media_from_url or list_posts. The only blemish is that the schema's type enum also allows document/audio, so the stated scope is slightly narrower than what the tool actually returns.

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 second sentence gives a concrete downstream use (feed the uid into create_post.media_uids), which implies 'use this to find attachable media'. It never says when to prefer add_media_from_url, create_upload_link, or delete_media instead, nor what happens when the library is empty.

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