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

Annotations only say it is a non-idempotent, open-world write; the description adds real behavioral context beyond that: it consumes the monthly music-video quota, requires the caller to hold music and video rights (no license granted), warns that lyric captions are speech-to-text and can be wrong on sung audio, and discloses the async job_id return pattern.

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?

Dense but front-loaded: format and duration first, then quota, then inputs, then caveats and next step. Every sentence carries information, though the single-paragraph block of eight-plus clauses is slightly heavier than it needs to 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?

For a 9-parameter creation tool with no output schema, the description covers the essentials: input modes, defaults, media-type-dependent requirements, legal caveat, caption accuracy risk, the returned job_id, and the polling step. Nothing an agent needs 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?

With 100% schema coverage the baseline is 3, but the description earns more by explaining cross-parameter behavior the schema states only piecemeal: gameplay/aesthetic pull from the SendShort library while custom requires video_url or video_path, and the default theme is intentionally not in list_themes. It still leaves details like the title fallback and audio_url vs audio_path precedence largely to the schema.

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 with hard constraints baked in: 'Queue a 9:16 music video up to 60 seconds.' It also names the async follow-up tool (get_music_video_status), so the agent can distinguish this creation tool from status-listing siblings 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?

Clear routing context: it tells the agent to call list_themes for caption styles, to poll get_music_video_status after submission, and to use POST /api/v1/music-video/upload before passing audio_path. It does not explicitly say when to prefer a different sibling (e.g. clip_video or schedule_short), so it stops short of full when/when-not coverage.

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