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

Annotations already declare readOnlyHint and non-destructive. The description adds valuable behavioral context: the tool's output differs based on whether a song is provided, prices are one-time and in USD, and it returns a full price list. No rate limits or auth requirements are mentioned, but these are less critical for a read-only pricing tool.

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?

Three sentences, front-loaded with the core purpose and then the two modes. Every sentence earns its place, though the final sentence about currency/one-time could be considered minor detail. Overall efficient and clear.

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?

Given one optional parameter, no output schema, and annotations covering safety, the description is complete enough: it explains what the tool returns in both modes and the pricing nature. It does not mention output format or pagination, but these are less relevant for a pricing lookup.

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 100%, so the parameter is fully documented. The description adds meaning by explaining that the song parameter is optional and that omitting it yields the standard price list. It does not add syntax details beyond the schema, but the dual-mode explanation is helpful context.

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 opens with a specific statement of purpose ("What licensing a Starchild song costs") and clarifies the dual behavior (with/without a song). It distinguishes itself from siblings like get_song or build_cart, but does not explicitly compare to them. No sibling directly overlaps, so a 4 is appropriate.

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?

The description implies when the tool is useful by describing two modes (with a song, without a song), but it does not explicitly state when to use this over alternatives like build_cart or how_to_sell_songs. The behavioral split is informative but not framed as usage guidance.

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