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

With no annotations, the description carries the full disclosure burden. It usefully adds two behavioral facts not in structured fields: pagination is capped at 50 and a $0.01 USDC cost applies when payments are active. However, it says nothing about return shape, whether the cost is per-request or per-item, or any auth/payment prerequisite, leaving real gaps for a paid endpoint.

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 short, front-loaded sentences with no filler: resource and filters first, then pagination and pricing. The telegraphic style ('hasta 50; $0.01 USDC cuando pagos activos') trades a little readability for density but every clause carries information.

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 four-parameter search tool with no output schema and no annotations, the description covers the filtering dimensions, pagination cap, and cost, which is most of what an agent needs. It stops short of describing the response contents or clarifying that all filters are optional, so it is adequate but not fully self-sufficient.

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 0%, so the description must compensate, and it does: 'por municipio o CCAA' maps to the municipio/ccaa filters, and 'consulta paginada hasta 50' explains limit/offset and imposes a real cap of 50 that the schema (max ~9e15) does not. It does not spell out offset semantics explicitly, but the pagination phrase conveys it. This is a meaningful improvement over the bare schema.

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 a specific resource (estaciones del registro oficial 2026) and the two filter dimensions (municipio, CCAA), so an agent knows exactly what it retrieves. The verb is only implied by the tool name (buscar), and it does not explicitly differentiate itself from siblings, but the sibling set (ITV-related tools, dataset request) has no obvious overlap so differentiation is not needed.

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 implied: query stations filtered by municipality or autonomous community, paginated. There is no explicit statement of when to prefer this over alternatives or which filters are required/optional, and no exclusion guidance is offered. For a narrowly scoped lookup sibling-free tool this is minimally acceptable.

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