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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description earns credit on top of that by interpreting data_confidence (high = official text; medium = translation or recent amendment via secondary source), disclosing provenance via sources[] and data_version, and noting 'Free.' Those are genuinely useful traits 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?

The scoping distinction is front-loaded and the parenthetical field lists are dense but purposeful, with zero filler sentences. The trailing 'Response:' block is the weakest part since it duplicates an output schema, but it is compact enough not to be wasteful.

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 one-parameter, read-only lookup with full schema coverage, annotations and an output schema, the description is more than sufficient and even over-delivers on return-value detail. The only material omission is guidance on its relationship to the sibling calculators, which is a usage issue rather than a completeness one.

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?

With a single parameter at 100% schema description coverage, the schema already explains the omit-vs-supply-code behavior fully. The description adds only the enumeration of what the rule table contains (articles, figures, dates, scope notes, URLs), which is table content rather than argument semantics. 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 makes clear this returns either the covered countries or a single country's full rule table, enumerated as articles, figures, effective dates, scope notes and source URLs. That is a recognizable verb-less but specific resource statement, and it is clearly distinct in spirit from the calculator siblings (end_of_service, notice_period, etc.). However, it never explicitly contrasts itself with those siblings or states the complementarity, so an agent must infer that this is the reference/coverage lookup.

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?

'Free.' signals a no-cost lookup, and the two usage modes (omit country vs. supply a code) are implied by the opening clause. But the actual omit/give instruction lives in the schema, and the description never says when to reach for this tool instead of the sibling entitlement calculators or whether it should be called first to obtain legal_basis. Usage is implied rather than prescribed.

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