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

Annotations already declare readOnly, idempotent, openWorld, so the safety profile is covered by structured data. The description adds real behavioral context beyond that: an unknown code returns found: false with guidance, and a bare indicator code describes every frequency variant. It does not discuss rate limits or the output shape in depth, hence a 4 rather than 5.

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 content is dense but front-loaded: the purpose verb and the list of what is explained lead, and the accepted-input and error behavior follow. Every clause maps to a real aspect of the response, though the long enumerations make it heavier than a minimal definition.

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?

An output schema exists, so return values need not be explained, yet the description still summarizes what the agent will get (definitions, units, codes, aggregates, classification), plus the input forms and the not-found behavior. For a single-parameter, well-schema'd read tool this is complete.

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 the baseline is 3, but the description adds meaning beyond the schema by clarifying that a bare indicator code expands to every frequency (schema only calls it 'a bare indicator code'). It also reinforces the accepted forms and lists a concrete example, though it largely parallels the schema's own guidance.

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 a precise verb+resource (explain/describe one ILOSTAT dataset) and enumerates exactly what the explanation contains: definition, unit/multiplier, frequency variants, breakdown codes, coverage, aggregates, and observation classification. It explicitly positions itself against the comparison/query siblings with 'before comparing numbers', so an agent can place it 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?

'Explain one ILOSTAT dataset before comparing numbers' gives a clear when-to-use signal that routes the agent away from ilostat_compare_geographies and ilostat_query_indicator. It does not explicitly name those alternatives or state exclusions, so it stops short of the top band.

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