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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered; the description still adds real context: ordering (newest first), the returned fields (numbers, hook, note, status), the status vocabulary, the saved_key for chaining, and the cost profile ("Uses no credits"). It stops short of saying whether results are capped or how to page beyond the limit, which is the one behavioral gap.

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?

A single dense sentence, front-loaded with the resource and scope before the routing advice and return details. Almost every clause earns its place, though the embedded field list (numbers, hook, note, status) makes it slightly packed and harder to scan than two shorter sentences would be.

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?

With only 2 optional params, no output schema and no nesting, the description covers what the tool does, when to use it, what it returns and what it costs — more than enough for a simple read tool. The only omission is limit/pagination behavior, which matters slightly given the maximum of 50.

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 50%: status carries its own description while limit has none. The description compensates for the status enum by mapping values to human labels (saved = To remake, used, archived), but says nothing about limit — no hint that it caps at 50 or what happens when more items exist. Partial compensation justifies the baseline 3.

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 ("Lists the posts the creator saved for inspiration") plus the source (viral searches, tracked creators), and explicitly separates it from the lookalike sibling list_library ("the creator's own saved drafts are in list_library"). An agent can distinguish it from list_library, get_library_item and find_viral_posts without opening any 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?

Gives an explicit use case ("Use it to pick a post to read or remix") and names the downstream tools it feeds (get_transcript, generate_content via saved_key). It also names the exclusion: own saved drafts live in list_library. When-to-use, what-to-do-next and the alternative are all present.

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