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 the safety profile is fully covered elsewhere. The description adds nothing beyond the retrieval verb — no note on payload shape, rate limits, or error behavior for an unknown slug — so it contributes almost no behavioral context.

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 short sentence that front-loads the verb and resource and closes with the identifying example. Nothing is wasted and nothing could be removed without losing information.

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?

For a one-parameter read tool with full schema coverage and annotations carrying the safety profile, the essentials are present. However, with no output schema, the description should say more about the returned payload ("ses numéros" is only a hint — cardinality, format, and empty-case behavior are unstated).

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%: the single slug parameter is fully documented and cross-references list_brands. The description adds an example value ("pole-emploi") but no format or validation detail beyond the schema, so the baseline 3 is appropriate.

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 a specific verb ("Récupérer") and resource ("un service et ses numéros"), and pins the lookup key to a slug with a concrete example. It is clear what the tool returns, though it never names its siblings (get_number, list_brands, search_numbers) to disambiguate the near-identical retrieval tools.

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?

There is no explicit when-to-use or when-not-to-use guidance in the description; the only hint that list_brands is a prerequisite lives in the schema's slug description ("tel que renvoyé par list_brands"), not in the tool description. An agent must infer why it would call this instead of get_number or search_numbers.

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