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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds meaningful context beyond those annotations: the ~90-day archive limit, the specific return fields (hammer price, bid count, close date), and the upstream API source. No contradiction exists between the description and annotations.

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?

The description is four short sentences, front-loaded with the core purpose, then categories, then return fields, scope, and source. There is no filler, repetition, or tangential detail. Every sentence earns its place.

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 all parameters documented in the schema and annotations covering the safety profile, the description fills the remaining gaps: what results look like and how far back the archive reaches. Since there is no output schema, the explicit mention of hammer price, bid count, and close date is valuable. Nothing essential for selecting or invoking the tool is missing.

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?

The input schema covers all 7 parameters with descriptions and an example, so the description does not need to add much parameter-level detail. It indirectly reinforces the days_back archive limit by mentioning 90 days, but it does not explain any parameter beyond what the schema already provides. Baseline 3 is appropriate given full schema coverage.

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 uses a specific verb ('Search') and resource ('closed ShopGoodwill auctions'), and immediately clarifies the tool's purpose: returning realized sale prices. It also lists the item categories covered, which helps distinguish it from a general auction search. The 'closed' versus regular search distinction is enough to separate it from sibling tools even without naming them.

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 clearly frames this as the price-comps tool for closed auctions, giving an agent strong context for when to use it. It does not explicitly name alternatives like shopgoodwill_search or shopgoodwill_item, nor does it state when not to use it. The context is clear, but exclusions and alternatives are left implied.

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