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

Adds meaningful behavior beyond annotations: latency ('10–40 seconds'), side effect ('Creates a new project each call'), and automatic transcription fallback when lyrics are absent. Annotations already cover mutation/safety profile, so this adds useful operational context without contradiction.

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, front-loaded with the core action, then latency and side-effect details. Every sentence earns its place with no redundancy.

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, and the description only partially covers returns by mentioning 'three visual styles' without describing response structure or pointing to choose_style as the next step. It otherwise gives enough for correct invocation, including the new-project side effect.

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%, so the baseline is 3. The description adds value by explaining that lyrics are optional and will be transcribed from audio if omitted, and it clarifies the expected audio formats (MP3/WAV), supplementing the nested audio object 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 ('Turns') and resource ('a song ... into a word-synced lyric video'), plus the immediate output ('proposes three visual styles'). It clearly distinguishes creation from sibling retrieval/export tools like get_lyric_video or export_video.

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?

Usage is implied by 'a song the user attached', but there is no explicit when-to-use versus alternatives (e.g., get_lyric_video, edit_lyrics) and no exclusions. Parameter-level guidance is present for lyrics, but the overall usage context is left to inference.

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