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

Annotations already declare the safe read-only, idempotent, non-destructive profile, so the description's job is to add context, and it does: latest published periods, source definitions, units, collection status, and the EL-vs-GR country-code convention. These are genuinely useful behaviors not derivable from the 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?

Three short sentences with no filler, and the source/scope constraint is front-loaded. Slightly terse to the point of ambiguity about whether it lists codes or series, but there is no padding to trim.

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?

An output schema exists, so return-value detail can be omitted, and zero params keep the surface small. However, the description never makes explicit what the tool actually enumerates (indicators vs country codes), leaving the core resource under-specified for a catalog-style tool.

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?

The tool takes no parameters, so there is nothing for the description to compensate for; baseline 4 applies. The country-code convention note is an extra courtesy but not required by the 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 reads as a noun phrase describing a dataset ('Eurostat EU/EFTA country codes and monthly/quarterly economic series since 2020') rather than stating a clear verb+resource. It does differentiate from World Bank siblings via the Eurostat scope and the Greece=EL note, but it never clarifies how this 'list' tool differs from the sibling get_economic_indicators.

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 only implied through the source scope: an agent can infer it is the right choice when Eurostat/EU-EFTA data is wanted and World Bank data is not. There is no explicit when-to-use, when-not-to-use, or named alternative among the many siblings.

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