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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds useful behavioral context: it returns up to 10 sample values per dimension, names the metadata fields (time range, observation count, last-update), and explains the downstream consequence of using invalid dimensions. This goes beyond the annotations without contradicting them.

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 three sentences with no filler. It front-loads the core purpose and return contents, then provides usage context and an alternative. Every sentence earns its place.

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?

The tool has only one required parameter, a rich output schema, and annotations covering read-only and idempotent behavior. The description fills in the remaining context an agent needs: why to call it, what it returns, and when to use a sibling instead. Nothing important 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?

The input schema has 100% description coverage for dataset_code, including an example and guidance to find codes via eurostat_search_datasets or eurostat_browse_themes. The description adds context about dimension codes (unit, na_item, geo) but does not add substantive parameter syntax beyond the schema. Baseline 3 is appropriate.

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 states a specific verb ('Fetch metadata') and resource ('a Eurostat dataset'), and enumerates the return contents: dimensions with valid values, time range, observation count, and last-update date. It also distinguishes itself from siblings like eurostat_get_dimension_values and eurostat_query_dataset, so an agent can tell what this tool is for.

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 explicitly says to call this tool before eurostat_query_dataset or eurostat_download_dataset, and explains why: eurostat_download_dataset builds its positional filter key from this dimension list, and filters naming absent dimensions are rejected. It also names eurostat_get_dimension_values as the alternative when the full set of dimension values is needed. This is clear when-to-use guidance with alternatives.

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