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

Annotations already cover read-only/idempotent safety, and the description adds genuinely new behavioral context: the Eurostat source dataset, the data vintage caveat (recent quarters get revised), and a cost of 1 credit. It does not describe the shape or ordering of what comes back, but the credit/revision notes are the operationally important extras.

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?

Front-loaded with what is measured, followed by the default behavior, then use-case examples, source, caveat, and cost. Every clause carries information an agent would otherwise have to guess; nothing is padding.

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 three-parameter, annotation-covered, no-output-schema tool, it covers measurement definition, scope, default mode, source, revisions, and cost. Only slight gap is that the returned structure (a quarterly series of percentage changes) is implied rather than stated.

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 geo codes, n, and the quarter/year enum are already documented in the schema. The description reinforces the default comparison mode (previous quarter) and the geographic scope, but adds no syntax or edge-case detail beyond the schema, so the baseline 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?

Names the exact measure (real GDP growth, seasonally and calendar adjusted, chain-linked volumes) and the exact population (one European country or EU/euro area), with the specific verb of returning quarterly changes. It is clearly separable from siblings like eu_house_price_growth, eu_inflation_rate, or next_gdp_release.

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 use cases in natural-language form ("is the German economy growing", "is Italy in recession") and states the default mode of comparison, which tells an agent when this tool fits. It does not explicitly route away from alternatives such as next_gdp_release or other Eurostat indicators, so it stops short of a full when/when-not specification.

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