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

Annotations already declare readOnly, idempotent, open-world and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: reporting years vary by indicator, earliest comparison values are included, source provenance is returned, and each call costs $0.003.

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?

One sentence, front-loaded with the action and result set, with cost appended at the end. The field enumeration is dense but every element maps to real return content, so little is wasted; it could be tightened slightly.

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, the description carries the burden of describing the return payload, and it does so reasonably well by listing the indicator components and the year-variation caveat. It is nearly complete for a two-parameter read tool whose annotations already cover safety.

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 both the country code and the optional goal filter are fully documented in the schema itself. The description adds no extra meaning (e.g., what an omitted goal yields or how multiple goals behave), leaving this at the baseline for a fully-covered 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 opens with a specific verb and resource: 'Return latest reported headline UN SDG indicators for a country,' and enumerates the returned fields (series, values, years, units, comparison values). The resource is clearly distinct from neighbors like get_country_report or get_economy_report, but no sibling is named to sharpen that boundary.

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?

There is no guidance on when to choose this tool over get_country_report, get_economy_report, or the other report tools. The only decision-relevant information is the $0.003 cost, which hints at a paid call but doesn't say when the data is worth fetching.

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