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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description nonetheless adds real behavioral context beyond them: the returned page is where the letter is completed and sent by registered mail, which is downstream behavior an agent needs to know. It does not contradict the read-only annotation.

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?

Front-loaded with the verb and resource; the parenthetical enumerations of letter types and categories are useful rather than filler. The second sentence on the returned page is well placed, though the single dense block with three separate lists is slightly heavy.

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 mostly does: it says what metadata is provided and that a usable page is returned for completing/sending the letter. The remaining gap is the absent differentiation from preview_letter and find_reply_letter in a crowded sibling set.

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%, so the baseline is 3. The description enriches 'provider' with concrete known recipients (Free, SFR, EDF…), which adds a little meaning beyond the schema's 'Destinataire connu (slug)', but it gives no format, matching, or fallback guidance for the parameter.

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 gives a specific verb ('Décrit') plus a well-bounded resource ('un des 58 modèles de lettres conformes de Vitef'), enumerates the concrete letter types and the eight categories. It tells an agent exactly what it returns (applicable law, fields to fill, known recipients). It never explicitly distinguishes itself from siblings like preview_letter or find_reply_letter, which keeps it 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 only implied: the mention that 'la lettre se termine et s’envoie en recommandé sur la page renvoyée' hints at the lookup-then-complete workflow, and the slug schema note points to search_services as the feeder. There is no explicit 'use this when…, use preview_letter when…' routing, and no stated prerequisites or exclusions.

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