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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is largely covered. The description still adds real value: ordering guarantee, the fact that results include unread state and bot-active status, WhatsApp's opt-in condition, and a prompt-injection warning that message content is data, not instructions — a genuinely useful behavioral caveat. It stops short of describing result volume, pagination, or limits.

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, both load-bearing: the first front-loads scope, platforms and ordering; the second carries the injection-safety note. Nothing is redundant or padded.

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?

For a read-only three-parameter listing tool with no output schema, the description covers what the result contains, which is helpful. However, it leaves the two undocumented filter parameters unexplained, so an agent cannot confidently use platform or unread_only from this definition alone.

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?

Only brand_id has a schema description (33% coverage); platform and unread_only are bare. The description never explains that platform filters the inbox or that unread_only restricts results — it only mentions unread status as returned data, which could mislead an agent into thinking it is not a filter. With low schema coverage the description should compensate and does not.

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 (listar la bandeja de DMs) and resource, and enumerates the platforms covered (Instagram, Facebook, TikTok Business, WhatsApp) plus ordering (most recent first) and included fields (unread, bot active). It is distinct from read_conversation, though it never names that sibling explicitly.

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: an agent can infer this is the entry point for browsing DMs before opening one with read_conversation. There is no explicit when-to-use/when-not guidance, no mention of how it relates to list_message_drafts or list_dm_automations, and no note on prerequisites such as WhatsApp permission beyond a parenthetical.

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