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

Annotations declare readOnlyHint=true and openWorldHint=false so the safety profile is covered, but the description adds real behavioral value: the result set is restricted to on-sale items, sorted cheapest-first, and each row carries best current retailer price plus retailer and date, list price, and the verdict/Guide link. That is meaningful disclosure beyond the annotations, though it doesn't cover result volume or pagination.

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 dense but well-ordered sentences — scope, filters/ordering, then result contents, then the sibling routing. Every clause carries information; the enumeration of categories in prose is slightly redundant with the schema enum-less description, but it is front-loaded and 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 no output schema, the description compensates by naming the returned fields (retailer price, retailer, date, list price, verdict, Guide link). Combined with filtering, ordering, and sibling routing, an agent has everything needed to call and interpret it correctly.

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%, so the baseline is 3, but the description adds semantics the schema doesn't: 'at or under a price' clarifies that max_price is an inclusive ceiling, and 'from one company' clarifies the company filter matches a single brand rather than a list. These are genuine refinements, not restatements.

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 (on-sale products), the required scope (one category, with the categories enumerated), and the output ordering ('cheapest first'). It also carves out the model scope (current and previous models) and routes pre-orders elsewhere, so an agent can separate it from list_products and get_release_calendar without opening any schema.

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?

Explicit about when this applies: on-sale items in one category, optionally narrowed by price ceiling or a single company. It also names the exclusion and the alternative explicitly — 'pre-orders and unreleased products are in get_release_calendar' — leaving nothing to inference.

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