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

Annotations already declare the safety profile (readOnlyHint, non-destructive, idempotent, closed-world), so the description is not burdened with that. It does add one useful behavioral note: the dates are relative to 'aujourd'hui', i.e., the result is dynamic and recomputed as of today. It says nothing about the response format or the number of dates returned.

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 padding, and the key outcome (first and last possible dates) is front-loaded. Efficient, though it could be marginally tighter given there is only one concern to express.

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 return-value burden and does so by naming what is returned (first and last possible dates). Annotations cover the safety profile. It stops short of describing the date format or optionality of the single parameter, but for a one-param, read-only lookup this is close to complete.

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%, and the enum for 'carte' is fully documented in the schema, so the baseline is 3. The description's phrase 'selon la carte choisie' merely confirms the parameter drives the result without adding syntax, default, or format detail beyond the schema.

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 resource and result: the first and last possible dates for transferring a number to Flytel, conditioned on the chosen card. An agent can understand exactly what the tool produces. It does not, however, differentiate itself from siblings like flytel_souscrire or flytel_verifier_rio, which also touch the portability journey.

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, no prerequisites, and no mention of alternatives. The caller must infer that this tool is for planning/reference before a transfer, but nothing in the text confirms that or excludes other tools. Comparable to the update_drive calibration, which earned a 2 for the same absence of guidance.

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