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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description adds genuinely non-obvious behavior: the sort order, the mentioned-in vs located-in distinction, and the Nigeria-returns-nothing quirk with its cause. Only the limit/offset and result-shape behavior are left unspecified, and there is no output schema to cover them.

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?

Front-loads the core operation and sort order, then the optional filter and its caveat. The long parenthetical on index frequency is dense but earns its place by explaining why Nigeria yields no results.

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 3-parameter read-only lister with no output schema, the description covers purpose, ordering, filter semantics, and a surprising edge case. It does not describe pagination behavior or the shape of returned entries, which are the remaining gaps.

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% and the schema's own country description already explains the mentioned-in semantics in near-identical terms. The description reinforces this and adds the Nigeria edge case, but does not clarify limit/offset beyond what the schema says, so it sits at the baseline for a partially 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?

States a specific verb+resource (list personnes from the IWAC index) plus the ordering rule (sorted by frequency, most-referenced first), which is enough to distinguish it from sibling listers like list_locations and list_subjects without opening a 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?

Provides clear conditional context: the 'country' filter selects mentioned-in rather than located-in entries, and it explicitly warns that Nigeria returns none and why. It stops short of naming an alternative tool (e.g. search_index) for name-based lookup, but the filter-routing guidance is strong.

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