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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so safety and idempotency are covered structurally. The description adds useful framing by enumerating what the answer contains (in-plan status plus call/SMS/MMS/data pricing), but says nothing about behavior for an unknown or misspelled country or any error/fallback handling. Adequate, not rich.

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?

Two sentences, no filler, and the routing instruction comes last where it is most useful. The purpose is slightly buried inside a colon-list construction rather than front-loaded as a single verb, but overall it is efficient and readable.

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 saying what comes back, and it does: in-plan status plus per-channel pricing and mobile-data treatment. Combined with a single well-documented parameter and full annotation coverage, this is nearly complete; only edge-case behavior for unknown countries 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?

There is one parameter with 100% schema description coverage, and that schema description already specifies accepted forms (French country name, e.g. « Maroc », or ISO alpha-2 code, e.g. « MA »). The description only says 'pour un pays donné' and adds no normalization or ambiguity guidance beyond the schema, so the baseline 3 applies.

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 and scope ('pour un pays donné : compris dans le forfait Flytel ... ou non, et sinon les prix des appels, SMS, MMS et ... données mobiles'), so an agent knows exactly what it returns. It also names the sibling it is not (check_usage_compatibility), making it unambiguous against the alternatives.

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 when-to-use ('À utiliser pour les prix hors forfait d'un pays') paired with an explicit alternative and its selecting condition ('pour savoir si un appel précis est compris (depuis où, vers où), check_usage_compatibility'). Nothing is left to inference.

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