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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds context the annotations cannot: the sort key and ranking definition, the fact that 'frequency' counts articles/publications/references rather than place occurrences, and the data-coverage caveat that no article is Nigerian — these materially shape interpretation of results.

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?

Purpose is front-loaded in the first clause, followed by the important caveat, and every sentence earns its place. There is mild redundancy: the 'mentioned-in, not located-in' point is made twice and largely duplicates the country parameter's schema text.

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 read-only, zero-required-parameter list tool with an output-less schema, this covers what an agent needs: what is listed, how it is ordered, and how the filter behaves counterintuitively. Minor gaps remain around tie-breaking within equal frequencies and the shape of individual entries.

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?

At 67% schema coverage the schema already documents limit and country well; offset is undocumented in both places. The description reinforces and sharpens the country parameter's semantics ('APPEAR IN' vs 'located in') in a way that matters for result interpretation, though it adds nothing about offset or how limit interacts with ranking.

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 specific verb and resource ('List lieux from the IWAC index') plus the default ordering ('sorted by frequency, most-referenced first'), which is more than a restatement of the name. However, 'lieux' is domain jargon left undefined, and differentiation from near-siblings like search_index, list_persons and get_place_distribution is only implicit through the absence of a query parameter.

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?

Gives strong situational guidance for the tricky part: the country filter is scoped as 'mentioned-in, not located-in' and readers are warned that foreign/cross-border entries appear and that Nigeria returns very few results. It stops short of naming when to pick this over search_index or get_place_distribution, so the routing guidance is incomplete rather than explicit.

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