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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: price freshness ('prix vérifié de moins d'1 h ou null'), fallback to alternatives when a product is unavailable, and that it returns a citable site URL.

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?

Front-loads the core purpose (detailed sheet by slug) before enumerating returned contents and the citation URL. The content list is long but every item is substantive, so density is justified rather than wasteful.

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 it does so thoroughly: description, editorial review, pros/cons, availability, price freshness, related comparisons, alternatives, and the citable URL. Nothing an agent needs to call and interpret this read-only tool correctly 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?

Schema description coverage is 100%, so the baseline is 3. The description goes beyond the schema by stating the provenance of the slug value (search_products or get_comparatif), which adds meaning about how the parameter should be sourced rather than just its format.

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+resource ('Fiche détaillée d'un produit') retrieved by a named key (slug), and explains that the slug comes from search_products or get_comparatif, which cleanly separates this detail-fetch tool from the search/list siblings. An agent can identify the operation and its input source without opening the 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?

The description gives a clear precondition and routing hint: the slug is obtained 'via search_products ou get_comparatif', so the agent knows it must search first and then fetch. It does not explicitly state when not to use it, but the prerequisite chain is clear enough that this is above implied usage.

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