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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces this non-redundantly: it explains that nothing is paid or debited and that the user pays for themselves on tchin.tech if they so choose. It also discloses the first-use authentication requirement. It stops short of describing result volume or ordering.

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 compact paragraph ordered sensibly: audience and auth, then what the data is with its fields, then the read-only guarantee. Every clause carries information, though the run-on sentence structure around the field enumeration is slightly dense.

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 compensates by enumerating the returned fields, and it covers the auth prerequisite and the no-side-effects guarantee. What is missing is disambiguation from mes_abonnements and any sense of result size or recency of the due dates, so it is strong but not 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?

The tool takes zero parameters, which is the baseline-4 case: there is no parameter semantics to convey and the description correctly spends no words on them. The field list it gives describes outputs, not inputs, so it does not mislead.

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 names a specific resource (the subscriptions the connected user pays to merchants, i.e. their prélèvements) and enumerates what it exposes: merchant, formula, amount, rhythm, next due date, delay, and the tchin.tech address. That is far more specific than the bare title. It does not, however, differentiate itself from the very close sibling mes_abonnements, which an agent would also plausibly pick.

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?

It establishes who it applies to (the user connected to their Tchin account, merchant or individual) and notes that connection is requested the first time, which is a real prerequisite. But there is no explicit when-to-use / when-not-to-use guidance, and the obvious alternative, mes_abonnements, is never named or contrasted.

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