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

The annotation already flags readOnlyHint=true, and 'Free' reinforces that this is a zero-cost read, with no contradiction. Beyond the annotations it discloses the return contract (engine enum values, optional question/asset_kind/song_brief, prompt, next_tool) and the fact that it may return a clarifying question, which meaningfully shapes agent behavior.

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 cost and purpose, then clean Args/Returns blocks. Dense but every line carries information; minor redundancy between 'names the studio' and the engine return list is the only waste.

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?

There is no output schema, and the description compensates by summarizing the return object and its key fields (engine options, question, next_tool). For a two-parameter read-only router this covers what an agent needs to call it and interpret results, with only minor gaps (e.g., what 'ask' engine implies).

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%, so the description must carry the parameters, and it does: message is 'the user's words (any language), 1-4000 chars' and hint 'forces that engine.' It clarifies the enum's effect (forcing a specific engine) rather than just restating the values, adding real meaning over the bare 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?

Specific: it 'reads what the user wants to make and names the studio for it,' so the verb (route/classify) and the resource (studio/engine) are both concrete. It also implicitly distinguishes itself as the entry point with 'call it first when the ask is vague.' It stops short of naming specific siblings it routes to, but the function is unmistakable.

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?

Gives explicit activation guidance: 'call it first when the ask is vague,' which tells the agent the precondition. It does not state when NOT to use it or name a concrete alternative tool for the non-vague case, so it falls short of a 5.

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