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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuine behavioral constraints not present in the schema: the period is mandatory and capped at 366 days, which affects how an agent constructs the call.

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, front-loaded with what is compared, followed by the hard constraint. 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 3-parameter, read-only aggregation tool this is nearly complete; 'vistas e interacción acumuladas por día' hints at a per-day time series. With no output schema, a brief note on the return shape (e.g., ranked posts with daily series) would close the remaining gap.

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 would be 3, but the description adds meaning the schema lacks by imposing the 366-day maximum span on from/to. The brand scoping guidance itself lives in the schema, so no extra credit there.

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?

Names a specific verb (compara) and resource (publicaciones de la marca), plus the metrics compared (vistas e interacción acumuladas por día) and the intent (cuál funcionó mejor). It is clearly a comparative analytics tool rather than a plain listing, which separates it from list_posts, though it never names those siblings 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?

The phrase 'para saber cuál funcionó mejor' implies the scenario for using it, but there is no explicit when-not guidance and no mention of alternatives like get_post_stats or get_post_stats per-post. An agent must infer that this tool is for cross-post comparison over a window.

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