Compare products

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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuinely new behavioral context that annotations cannot convey: `cheapest` names the lowest-priced in-stock item, `common_ingredients` lists components shared by all products, and ingredient amounts are expressed per `ingredients_per` which may differ across products. It does not mention error handling or how invalid/duplicate product references are treated.

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 tightly packed sentences: capability first, workflow placement second, output-field and unit caveats third. Every sentence contributes distinct information with no filler or repetition of the schema.

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 a single required parameter, rich annotations, a fully documented schema and no output schema, the description supplies exactly the missing piece: what the response contains (`cheapest`, `common_ingredients`) and the caveat that per-serving units are not directly comparable. Nothing an agent needs in order to call and interpret this tool is absent.

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 parameter's own description already explains both the id and path/URL accepted forms. The description restates the 2-to-5 bound already enforced by minItems/maxItems and adds no new semantics about the products parameter itself. Baseline 3 is appropriate since the schema carries the load.

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 (compare 2-5 products side by side) and enumerates exactly what dimensions are compared: price, stock, rating, properties, ingredient amounts and dosage. The count range and the named sibling tools make it immediately distinguishable from dr_product (single product) and dr_search (discovery).

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?

Explicitly positions the tool in a workflow: use it after dr_search / dr_cheapest / dr_related to choose between candidates, with a concrete scenario (three magnesium supplements). The only mild gap is an explicit when-not statement (e.g. use dr_product for a single item), but the precedent tools are named so the path is unambiguous.

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