largest_areas

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

Annotations already establish this as a safe, non-open-world read, so the description's job is to add domain behavior — and it does: the default window is the latest four quarters, formation-agent addresses are excluded to avoid registered-office artifacts, and results carry a likely range and rank rather than point counts. It does not discuss how ties or boundary cases in the range/rank are handled, which keeps it short of a 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?

Three tight sentences: what it returns, the default period and unit of comparison, then the explicit exclusion and the growth-tool redirect. The leading question frames the use case efficiently and nothing is redundant.

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 six-parameter aggregation tool with an output schema, the description covers the key interpretive facts an agent needs: default period, ordering, output shape (range and rank), the formation-agent exclusion, and the size-vs-growth distinction. The remaining detail (levels, limits, closed-company counting) is delegated to a well-described schema, which is reasonable.

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 83%, so parameters are already well documented — notably sic_codes, whose schema text carries the format rules, examples and bundling guidance. The description only reinforces 'with these codes' and the default four-quarter period, adding little meaning beyond the schema. Baseline 3 is appropriate here.

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 operation on a specific resource: the council areas/regions/nations of Great Britain with the most companies registered under given SIC codes in a period, ordered largest first, returning a likely range and rank. It also explicitly separates itself from a sibling ('Size, not growth'), so an agent can tell it apart from rank_areas_against_great_britain without opening either 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?

Gives a clear use condition (measuring size/concentration, not growth) and names the alternative to use for growth questions. It also states the default period, which matters for interpreting results. It does not address other plausible siblings such as compare_two_areas or compare_area_with_great_britain, so routing is good but not exhaustive.

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