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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds context they don't carry: the calculation is comparative and derives new figures (monthly-normalized price, savings gap) rather than just fetching a record, and there is no cost or side effect on the catalog. It stops short of explaining how the monthly figure is derived or what happens when no cheaper equivalent exists.

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 sentence with no filler, and the precondition (a box bought at a price) is front-loaded before the list of outputs. It is dense, though — four outputs chained with nested parentheses ('même forme, dose proche, qualité au moins égale') make it heavier to parse than necessary.

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?

There is no output schema, so the description must carry the return contract, and it does: four named outputs are enumerated. Inputs are fully documented by the schema. The remaining gap is edge-case behavior (what is returned when no cheaper equivalent exists, or which price 'prix relevé' draws from), which a verifying tool of this kind would benefit from stating.

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%: 'produit' is documented as an ID, URL or name+brand, and 'prix_paye' as euros. The description adds nothing about the parameters, but it doesn't need to — baseline 3 applies when the schema does the work.

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 states concretely what the tool returns for a given purchase: price per month at the paid price, the recorded price for the same box, a cheaper equivalent product (same form, similar dose, at-least-equal quality), and the monthly gap versus the product Sous La Gélule promotes. That is a specific, non-tautological purpose. It does not, however, explicitly distinguish itself from the sibling 'meilleur_choix', which sounds like a neighboring recommendation tool, so it falls short of a 5.

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 opening 'Pour une boîte achetée à un prix donné' implies the situation (you already bought a box at a known price), which gives implicit when-to-use guidance. But no alternative tool is named, no exclusion is stated, and nothing tells the agent whether this supersedes or complements 'meilleur_choix' or 'chercher_produit'.

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