assign_lyrics

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

No annotations are supplied, so the description carries the full behavioral burden. It usefully discloses the mutation effect (new consecutive notes are created from start_tick) and the list-repetition rule, but says nothing about whether existing notes or lyrics in that region are overwritten, how many notes result, or what is returned.

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?

Two sentences, front-loaded with the action and the anchoring parameter, with the list-behavior caveat following. The duplicated English/Japanese text roughly doubles length, but that is a deliberate localization choice rather than 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?

With six parameters, zero schema descriptions, no annotations, and no output schema, the description should do more. It adequately covers start_tick, tones, and durations, but leaves part, text, and language undefined, so an agent still has to guess at half the inputs.

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% across six parameters, so the description must compensate. It does explain the two most complex parameters, tones and durations, including the single-value vs list form and the last-value-repeats rule, but part, text, and especially language ('auto') get no meaning added at all.

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?

The description states a specific verb pair and resource: split text into lyrics and lay out new consecutive notes anchored at start_tick. That is concrete enough to picture the effect, but it never distinguishes this from siblings like set_lyrics, replace_lyrics, or split_lyrics, so an agent cannot route between them from this text alone.

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 only implied: the description makes clear it is for turning a text string into a sequence of notes on a part, but there is no explicit when-to-use versus when-not, no mention of prerequisites, and no named alternative for the closely related lyrics tools.

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