Sources, licences and legal basis

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

Annotations already declare read-only, idempotent, closed-world behavior, and the description still adds substantial context beyond them: 'no network', every answer derived from a dated snapshot, snapshot_date and attribution line always attached, the legal note that the Navigator is not binding while delegated acts are, and a quoting convention that wraps remote text as an explicit non-instruction. That is meaningful operational and safety behavior, not a restatement of 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?

The first sentence is well front-loaded and answers the core question immediately, but the long comma-chained enumerations of regulation numbers and licence identifiers make the body a dense wall of text that is harder to scan than it needs to be. The precision is largely justified, yet some of the listing is closer to reference material than selection guidance.

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 parameters, no output schema, and no nested structures, the description carries the full burden and does so: it names the snapshot source, the fields returned, the licensing terms, the legal acts, and the quoting convention. An agent can call this tool and interpret its output without further documentation.

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 zero parameters, so the schema imposes no documentation burden and the baseline is 4. The description correctly avoids inventing inputs and instead describes the fixed payload each call yields.

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 enumerates precisely what the tool returns: snapshot/NACE dates, counts, SHA-256 hashes, licences with quoted terms, CELEX/ELI legal acts, annex mappings, and Navigator-vs-Official-Journal diffs. That is clearly distinct from data-lookup siblings like search_activities or get_activity, though the opening phrase 'Where the data comes from' is nominal rather than a stated verb.

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 — consult this when you need provenance, attribution, licensing or the legal basis for other answers — but there is no explicit 'use this when / not when', no mention of alternatives, and no statement that the other sibling tools do not provide this metadata.

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