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

Beyond the annotations, the description discloses concrete side effects: a draft is saved, a review widget is rendered, repeated calls create separate drafts (concretizing idempotentHint=false), and crucially that no credits are spent and no sign-in is required. It resolves the tension between readOnlyHint=false and destructiveHint=false by explaining the write is a non-costly draft.

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?

Front-loaded with the core action and its cost/auth guarantees, and the exclusion list is compact. The later sentence 'Use this only to create a new song from a style description and (optional) lyrics' partially restates the opening, a minor redundancy that keeps it from a 5.

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 7-parameter tool with an output schema and full annotation coverage, the description supplies everything an agent needs: cost, auth, side effects, idempotency semantics, prerequisites, and routing exclusions. Return values need not be explained because an output schema exists.

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 86%, above the high-coverage threshold, so the schema already documents style, lyrics, model_id, duration_sec and instrumental well. The description only adds the workflow hint that lyrics should be authored in-conversation first, and leaves model_name's relationship to model_id unexplained. Baseline 3 is appropriate.

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+resource (prepare an Abracadabrax song from a style brief with optional lyrics/title) and immediately distinguishes it from generation ('Nothing is generated'). It also carves out what it is not, which lets an agent separate it from generate_song and update_song_project 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?

Explicit when-to-use ('only to create a new song from a style description and (optional) lyrics'), explicit workflow prerequisite ('write the lyrics in the conversation first'), and an explicit exclusion list (covers, remixes, extending, editing, stem separation, voice cloning, transcription). Nothing 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.