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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so safety is covered. The description adds genuinely useful context beyond them: the exact figures returned (gross, fee incl. reseller share, net before card fee, refunds), the output shapes (rows, totals, CSV), and the key requirement.

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?

A single dense sentence, front-loaded with the actor and resource, with a parenthetical breakdown of report contents. Every clause carries information, though the parenthetical packing is heavy.

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 no output schema, the description compensates by naming the returned figures and formats (rows, totals, CSV), and it flags the auth requirement. For a one-param read-only statement tool this is essentially complete, missing only pagination/limit details.

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% and the single optional param (month) is fully documented with its YYYY-MM format and default. The description reinforces the monthly scope ('one month') but adds no syntax beyond the schema, so the baseline 3 applies.

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 resource (one month of delivered sales for a seller's books) and enumerates the report components, so the agent knows exactly what it retrieves. It does not explicitly distinguish itself from close siblings like seller_fees or my_orders, so no sibling routing guidance is present.

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 leading 'Seller:' scopes the audience and 'Needs your key' implies an authenticated-seller context, so usage is implied. There is no explicit when-to-use-this-vs-alternative guidance (e.g., versus seller_fees or my_orders), leaving the agent to infer.

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