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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered; the description reinforces rather than contradicts them with "Risco: read · Efeitos: Nenhum". It adds information the annotations do not carry: the authorization scope (messages:draft) and the fact that the tool may be unavailable under the current grant — genuinely actionable context.

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 compact lines: the substance (what templates are, what variables they contain) comes first, followed by the scope/risk/effects/availability line. No filler, no repetition of the title, and the operationally critical unavailability warning is not buried.

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 parameters and no output schema, the description supplies what an agent needs: the nature of the items returned and their variable placeholders, the read-only risk profile, and the permission gate. It could mention ordering or whether custom templates include archived ones, but that is a minor gap for a zero-argument list tool.

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, so there is nothing for the description to disambiguate; the schema is empty and coverage is nominally 100%. Baseline 4 applies. The mention of template variables is about returned content, not input, so it neither helps nor hurts here.

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 the resource precisely (message templates) and enumerates the subtypes — online check-in, voucher, custom — plus the interpolatable variables ({{nome}}, {{link_checkin}}), which is concrete detail an agent can recognize. It lacks an explicit verb and does not name a sibling such as list_guest_messages or draft_guest_message to disambiguate, so it stops 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?

There is no explicit when-to-use or when-not-to-use guidance, and no alternative tool is named — an agent must infer that this is the read-only catalogue lookup rather than the message-sending siblings. What it does provide is an availability gate ("INDISPONÍVEL nesta autorização") plus the required scope messages:draft, which tells the agent whether calling is even possible.

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