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

With readOnlyHint/idempotentHint/destructiveHint already covering the safety profile, the description adds real value beyond annotations: it clarifies that nothing is stored and the check runs in memory, and that the RIO check is a key/checksum validation. It does not describe the response shape, but the read-only nature is fully conveyed.

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 tight sentences, purpose front-loaded, with the non-persistence guarantee immediately following. No filler or redundancy.

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 read-only verification tool with rich annotations and a fully documented 2-param schema, the description covers intent and behavior sufficiently. The only gap is that it does not spell out the exact outcome returned (e.g. the possible verdicts), though with no output schema this is a minor omission.

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 echoes the RIO 'clé' concept already explained in the schema, and adds no format or parsing guidance for the optional 'rio' or the required 'numero' beyond what the schema states.

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: it reports whether a mobile number can be ported to Flytel and whether the RIO code matches, plus mention of the checksum/key check. The purpose is unmistakable and no sibling tool performs RIO verification. It does not explicitly contrast itself with siblings, keeping it just 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?

Usage is implied by the purpose (a pre-portability verification step) but there is no explicit when-to-use, when-not, or pointer to alternatives such as flytel_souscrire or flytel_dates_transfert. An agent can infer the context but is given no routing guidance.

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