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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds value beyond them: the ordering (most-played first), a per-row billing model where `limit` caps cost, and a prompt-injection warning that the content is user-generated and untrusted. That is meaningful operational context an agent cannot get from structured fields.

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?

Four compact sentences, each carrying distinct information: purpose+ordering, use case+alternative, return shape+billing, and a safety caveat. Front-loaded and zero filler.

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, but the description compensates by listing the returned fields (pk, user_pk, mix_name, item_total, play_count). Combined with the cost model and untrusted-input caveat, an agent has everything needed to 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% and both params are documented, so baseline is 3. The description adds meaning beyond the schema by tying `limit` to cost ('caps both rows and cost') and enumerating the returned columns, which the schema does not express.

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 ('Get a TikTok user's playlists (mixes), most-played first') and names the sibling it is not: `get_tt_playlist_by_id`. An agent can distinguish it from the ~45 sibling tools without opening either 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 ('see how a creator groups videos') and routes to the correct alternative with its condition ('use `get_tt_playlist_by_id` for one playlist's description and cover'). When-to-use and when-not-to-use are both present.

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