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

Annotations only declare readOnlyHint=true; the description adds substantive behavioral context by naming the per-country attributes returned, including the three-state pricing model (priced online, quoted, or not offered). It omits anything about result size, ordering, or whether unsupported countries appear, so it stops short of full transparency.

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?

A single dense sentence, front-loaded with the key fact (ISO country codes) and then the field meanings; nothing is redundant. The nested relative clauses for pricing make it slightly harder to parse than it needs to be.

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 output schema and no parameters, the description carries the burden of explaining return values, and it does so adequately by enumerating the flags per country. Remaining gaps are minor: no indication of how many countries are returned or whether the list is filtered to supported countries only.

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?

Zero parameters, so the baseline is 4, and the description goes further by tying the returned codes to the specific sibling-tool parameters (country_of_use, customer_country), clarifying expected value format indirectly via the ISO 3166-1 alpha-2 reference.

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?

States the resource precisely (ISO 3166-1 alpha-2 country codes) and enumerates the metadata attached to each entry, so an agent knows this is a country lookup with apostille/sworn-translation/pricing flags. It is distinguishable from list_languages and get_coverage by subject matter, though the leading verb is implicit (the description leads with the return payload rather than 'lists').

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?

Implies when the data is needed by naming the two downstream parameters it feeds (country_of_use for translation, customer_country for VAT), which is a useful usage hint. However, there is no explicit 'call this before X' instruction and no mention of alternatives or preconditions.

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