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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so safety is covered. The description adds meaningful context beyond that: it caps input at 5 shops and explicitly discloses a negative capability ('No revenue estimate'), preventing an agent from over-promising revenue figures. Return format and error behavior for invalid shop names are not covered.

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 compact sentences, front-loaded with what is returned and immediately followed by scope caveats and usage. Every clause carries information; the parenthetical on transaction_sold_count is dense but earns its place by preventing a common misinterpretation.

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 carries the burden of describing return values and does so by enumerating the four metrics plus the explicit absence of revenue. For a single-parameter, read-only lookup this is nearly complete; only the response shape and handling of invalid or missing shops is unaddressed.

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%, and the schema already documents the shops parameter, including the array-or-comma-separated-string forms and the maxItems of 5. The description reinforces the 5-shop cap and clarifies the shop-level semantics of the sales figure but adds no new syntax or format guidance. 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 and resource: returns Etsy shop-level sales count, active listings, favorites and opening year for up to 5 shops. It also disambiguates from siblings by scoping to shop-level metrics rather than audits, rank checks, or top-shop lists, and clarifies that transaction_sold_count is total shop sales, not per listing.

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 use cases: 'how many sales does this Etsy shop have?' and comparing competitors, which tells the agent when to reach for it. It stops short of naming alternatives or exclusions, so an agent choosing between this and etsy_shop_audit or etsy_rank_check must infer the boundary.

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