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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description goes beyond this by disclosing the per-call price in USD with x402 on Base, and by enumerating what the result contains: period, unit, whether it is an estimate, and the dataset citation. This is useful operational context that the annotations do not provide.

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?

The description is two tightly scoped sentences with no filler. The first sentence front-loads the tool's purpose and result fields, and the second states the cost. Every part earns its place, and the structure is easy to scan.

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?

With no output schema, the description carries the burden of explaining both the return shape and how to invoke the tool. It does mention the return components and price, but it omits parameter value guidance and does not explicitly route the agent toward indicador-ine when Spanish national statistics are needed. This leaves a meaningful gap for correct invocation.

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 0%, and the two parameters have no types, descriptions, or enums. The description broadly maps 'pais' to an EU country and 'indicador' to inflation or unemployment, but it does not specify accepted string values, codes, or formats. An agent still has to guess whether to pass 'ES' or 'España', and whether 'indicador' should be 'inflacion', 'IPCA', or another value.

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 identifies a specific data-retrieval resource: the latest Eurostat inflation (IPCA) or unemployment value for an EU country, and lists returned fields such as period, unit, estimation flag, and dataset citation. It is clear but phrased as a noun phrase rather than a verb, and it does not explicitly distinguish itself from the sibling tool indicador-ine, though 'según Eurostat' implies the difference.

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 implies the tool is for EU-country Eurostat inflation/unemployment lookups, which gives the agent a reasonable context signal. However, it provides no explicit alternatives, exclusions, or guidance about when to prefer this tool over the closely related indicador-ine. The division of labor with that sibling is left to inference.

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