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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered; the description adds genuine value beyond them by disclosing the auth scope and the plan-gated error contract. It does not mention result volume, pagination, or cost, but the output schema already covers the 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?

One sentence states what the tool returns and the dimensions; a second states the access requirement and failure mode. Nothing is repeated and the substantive purpose is front-loaded before the gating detail.

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, plan-gated statistics tool with a full output schema, the description covers purpose, dimensions, auth, and the denial case. It stops short of saying how both-optional parameters behave when omitted (aggregate across all provinces/types) or any result-size characteristics.

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%, with both `tipo` and `provincia` documented including the lowercase-slug pattern (p. ej. `madrid`). The description names the two dimensions but adds no format, matching, or cardinality detail beyond the schema, so the baseline of 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 concrete resource (estadísticas de subastas resueltas) with the specific metrics returned (tasa de adjudicación, descuento real, precios) and the two grouping dimensions (provincia, tipo de inmueble). This is clearly more specific than a restatement of the title, but it never distinguishes itself from the nearby sibling estadisticas_publicas, which an agent could plausibly confuse it with.

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?

Gives concrete preconditions: an account with scope `informes:read` and a Pro-or-higher plan, plus the failure mode (`plan_required` with `locked`). What is missing is any explicit routing guidance against alternatives such as estadisticas_publicas or analisis_subasta, so the agent knows the gating but not the boundary case.

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