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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond that: the data provenance and vintage (World Bank 2024) and the multilingual input contract, which tells the agent this is a stable, offline-style dataset lookup with no side effects. It does not contradict the annotations. Return-value behavior is not described, but an output schema exists to cover that.

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?

Two sentences, front-loaded with the returned fact set, then the accepted input forms. No filler or marketing language. Slightly dense enumeration, but every clause carries information an agent needs.

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 two-parameter read-only lookup with a full output schema, the description covers purpose, content and accepted inputs adequately. Minor gap: it doesn't state behavior on an unknown country or ambiguous name, which would matter for error handling, but nothing essential for calling the tool correctly 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?

Schema coverage is 100%, so both parameters are already documented, including the locale enum and the ISO code example. The description restates the supported languages for the country parameter, which reinforces but does not meaningfully extend the schema (e.g. it doesn't say whether locale affects the response language versus name matching beyond what the schema states). 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 names a specific resource (one country) and enumerates the concrete fields returned: capital, region, population, area, languages, currencies, driving side, neighbours. An agent can tell it apart from siblings like search_countries or compare_population by scope (single country, full fact sheet), though no sibling is named explicitly.

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 by the scope ('one country') and the accepted input forms, so an agent can infer this is a single-record lookup rather than a search. However, there is no explicit statement of when to prefer this over search_countries or get_borders, and no exclusions or prerequisites are given.

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