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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, and the description adds genuine behavioral detail: each value carries its own period and chart link, projections are labelled, and codes lacking data are returned separately. That missing-data contract is the kind of thing an agent would otherwise have to discover by trial.

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?

Three dense sentences, front-loaded with the core scope before the behavioral details. Every sentence carries information, though the middle sentence packs two distinct facts (period/chart link and projection labelling) into one semicolon-joined clause.

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?

There is no output schema, so the description has to convey the return shape, and it does: one value per entity plus its period and chart link, projection flagging, and a separate bucket for codes with no data. Nothing essential for calling or interpreting the result 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 description coverage is 100%, so all three parameters are already documented, including the 'omit for latest observed value' behavior for year and the ISO3 constraint for countries. The description restates the year-omission semantics but adds no syntax or constraint beyond the schema, which is the baseline case for a fully documented schema.

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 and resource: returning a single indicator value across up to 20 countries for a chosen or latest year. This scope implicitly and clearly separates it from get_indicator_series (one country over time) and search_indicators, so an agent can route correctly without opening the schema.

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 comparison framing (up to 20 countries, one value per country) implies when this tool is appropriate, and it explains what happens when year is omitted. However, it never names an alternative tool or an explicit when-not condition, so the routing guidance is left to inference.

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