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 behavior the annotations cannot convey: per-row billing, that `limit` caps cost as well as rows, and that results are untrusted user-generated content. No mention of pagination or caching, but the cost and trust disclosures are substantive.

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 tight sentences with the ranking purpose front-loaded, followed by alternatives, return shape, cost, and trust warning. Every sentence earns its place; the only minor cost is density.

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, yet the description enumerates the returned columns (pk, user_pk, mix_name, item_total, play_count) and the cap semantics. For a single-parameter ranked-list tool, nothing needed to call it correctly is missing.

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 documents the 1-100 range, so baseline would be 3. The description goes further by explaining that `limit` gates both row count and billing cost, which is a semantic dimension the schema cannot 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 (rank), a specific resource (TikTok playlists/mixes), and the ordering dimension (play count across the database). An agent can distinguish it from get_tt_playlist_by_id and search_tt_playlists purely from the description.

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?

Explicitly names the use case ('find the most-watched series') and the alternative tool with the condition that selects it ('use search_tt_playlists to narrow by name'). Routing is unambiguous.

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