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

Annotations already establish readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds value beyond them: the sort order (newest first) and the exact returned fields (video_id, file name, duration, size, preview link), which is what lets an agent chain into create_tiktok_ad.

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 front-loaded sentence; the purpose and return payload come first and the 'why' follows. The em-dash parentheticals make it slightly dense but nothing is wasted.

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 values need not be re-explained, and the safety profile is fully covered by annotations. The gap is parameter documentation: an agent cannot tell what limit does or whether advertiser_id defaults matter, which leaves the definition under-complete for a two-param call.

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 0% and both parameters (limit, advertiser_id) are undocumented. The description alludes to 'the ad account's' library but never maps that to advertiser_id nor explains limit/pagination, so with two opaque params it fails to compensate for the schema 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 (Lists) and resource (the ad account's VIDEO LIBRARY) with scope detail — 'every video material uploaded to TikTok Ads, newest first' — and explicitly names the sibling it feeds (create_tiktok_ad requires the returned video_id). An agent can distinguish it from list_tiktok_asset_groups or upload_tiktok_video without opening a 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 a concrete when-to-use case: 'pick "the video I uploaded last" instead of guessing an id.' That is clear routing context, but it does not name alternative tools (e.g. upload_tiktok_video when no video exists yet, or the ad/asset-group listers) or state exclusions.

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