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

Annotations already declare readOnlyHint and idempotentHint true, and the description adds substantial behavioral context on top: plan-gated fields return `locked` with `upgradeUrl`, `orden: score` silently falls back to `recent` and `solo_viables` is ignored (with a `degradado` field), and there is a 20-per-page cap. This gives an agent an accurate model of what the response will contain across account tiers. No contradiction with annotations.

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?

Four dense sentences with zero filler: the purpose and filter scope are front-loaded, followed by access model, plan-gated data behavior, degradation behavior, and pagination cap. Every clause carries operational 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?

For a 15-parameter tool with 100% schema coverage, an output schema, and safety annotations, the description covers the remaining critical ground: access tier, exactly which derived fields are gated, how gating manifests in responses (`locked`/`upgradeUrl`/`degradado`), and pagination limits. Nothing an agent needs to call and interpret this search correctly is missing.

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 individual parameter meaning is already documented; the description adds cross-parameter, plan-dependent semantics that the schema cannot express, such as `orden: score` degrading to `recent` and `solo_viables` being ignored without Pro. It also bundles the two zone parameters as 'zona (bbox o radio)', helping an agent see that `bbox` and `cerca` are alternatives for the same filter intent.

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 ('Busca subastas judiciales de inmuebles del BOE') and enumerates eight filter dimensions (provincia, municipio, tipo, precio, superficie, texto libre, zona, estado). This scope clearly distinguishes it from siblings like `subasta` (singular) and `buscar_por_codigo`, whose names imply narrower lookups. The access model ('Pública, sin cuenta') further pins down its role as the open multi-filter search.

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 gives clear context: it is the public, account-free search over BOE auctions, and it explicitly explains plan gating (Pro required for scoring, veredicto, cargas, ROI, valoración, intervinientes) plus degraded behavior without a plan. However, it never names sibling tools or states explicit when-not-to-use conditions, so exclusion guidance 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.