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

With no annotations, the description carries the full burden and does substantial work: it discloses ordering ('in the order they held the post'), provenance (Wikipedia list with revision id), and a cross-source verification rule against Wikidata. The critical caveat — a missing name means the sources disagree, not that the post was empty — is exactly the kind of non-obvious behavior an agent could not infer elsewhere. It stops short of describing the returned structure or any rate/auth considerations.

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?

Two sentences, front-loaded with the 'who led whom and when' framing, followed by the sourcing caveat. Dense but every clause carries information an agent needs, with no filler.

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 two-parameter, read-only lookup with no output schema and no annotations, the description covers scope, ordering, provenance, and the key caveat about gaps. What remains underspecified is the shape of the return (post titles, date ranges, revision id placement), which an agent would have to discover by calling.

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 100%, so both parameters are already documented, including examples and the omit-for-all-states behavior. The description reinforces the year range and adds the notion that results are tied to the same post over the same years, but contributes little syntax or format detail beyond 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 resource (heads of state, heads of government, ruling-party leaders) with an explicit verb-like framing ('who led a country') and a bounded scope (1800-2025). It is immediately distinguishable from siblings like get_country or get_year_facts, which do not return leadership rosters.

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?

The description implicitly tells the agent to supply a country for a single state and to omit it for all states, and the year bound is stated. However, it never names an alternative tool or states when this should be preferred over get_country, get_timeline, or search_history, so routing between siblings is left to inference.

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