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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so safety is covered structurally. The description adds genuinely useful context beyond that: sender coordinates are excluded from the preview, and the PDF plus registered-mail sending occur on the returned page rather than as a side effect of this call. It stops short of describing pagination or return shape.

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, zero padding, with the core action stated first and the scoping/where-the-rest-happens caveat second. Every clause carries information an agent needs.

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?

There is no output schema, and the description partly compensates by explaining what the returned page is for (PDF and registered mail). Combined with full schema coverage of all three parameters, the definition is nearly sufficient; only the exact preview/return format is left unstated.

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 slug, values and provider are already documented in the schema (including the pointer to get_calculator/get_quote for field keys). The description only adds that sender coordinates are not among the supplied fields, which is marginal added meaning. 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 verb and resource: it drafts the text preview of a Vitef letter from field values. It also bounds the scope (no sender contact details) and clarifies that PDF generation and registered mailing happen elsewhere, which separates it from full-letter or send operations. It does not name a sibling directly, so differentiation is inferential rather than explicit.

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?

The description implies this is the preview step before PDF/sending, but it never states when to choose it over siblings such as get_letter, get_calculator or estimate_quote. The cross-references to get_calculator/get_quote appear only in the schema, not in the description. Usage is implied rather than stated.

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