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

Annotations already declare this a safe, idempotent, non-destructive read. The description goes beyond them by disclosing the ranking logic (index frequency computed from articles + publications + references), the cross-border/foreign-result behavior, and the Nigeria edge case — real behavioral context an agent needs. Return shape is still unstated.

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 and ordering are front-loaded in the first clause, then the country caveats follow. The parenthetical Nigeria explanation is long but earns its place as a genuine edge case; overall slightly dense but well-structured.

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 list tool with no output schema and no annotations gap, the description covers filtering and ordering well, but never describes the entry fields returned (name? frequency value? country?). An agent can call it but cannot anticipate the payload shape.

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 67%, but the description adds decisive semantics the schema only hints at: 'country' selects entries MENTIONED IN records from that country, not located there, and ranked by collection-wide frequency. That materially changes how an agent interprets the filter, though limit/offset behavior is left to the 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?

States a specific verb and resource ('List lieux from the IWAC index') plus the ordering ('sorted by frequency, most-referenced first'), so the agent knows exactly what comes back and in what order. It doesn't explicitly distinguish itself from the nearby list_persons/list_subjects/search_index siblings, keeping it just short of a 5.

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?

Provides strong conditional guidance around the 'country' filter, including an explicit negative case ('Nigeria returns none here' because the index frequency draws on articles/publications/references). It never names an alternative tool for the filtered cases, so it lacks full when-to-use/when-not routing.

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