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 that day/time default to the current time in JST, that department/service breakdowns are truncated to top 15 / top 10, and that childcare coverage is limited to Tokyo and Osaka-city pilot records with coordinates only. Remaining gaps are operational (latency, caching, error behavior), which are minor for an aggregation read.

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-loaded: the first clause states the operation, scope and use case before the long output enumeration. The enumeration is dense and unstructured (one continuous paragraph, no bullets), but with no output schema almost every listed field earns its place for an agent judging output fitness.

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?

There is no output schema, so the description must explain return values — and it enumerates them thoroughly across all four data domains, plus defaults, truncation limits and data-coverage caveats. For a complex, five-parameter aggregation tool this is complete enough to invoke correctly.

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 description coverage is 100%, so the schema already documents all five parameters including ranges and the HH:MM pattern. The description adds the meaningful link that day and time jointly define the 'open at that day/time' count metric, but it does not add syntax or interpretation beyond that.

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?

Specific verb+resource: aggregates medical/care/childcare facilities and population within radius_m of a lat/lon point, and names the use case (商圏分析・営業地域調査). It also explicitly differentiates from the sibling list-style tools with '個別施設の一覧ではなく集計値のみを返します', so an agent can tell it apart from search_nearby/get_facility 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?

It gives a clear usage context (trade-area / sales-territory analysis) and a negative guide — it returns aggregates only, not individual facility lists — which steers an agent away from using it as a facility lookup. It never names a specific sibling (e.g. search_nearby) as the alternative, so the routing is implied rather than explicit.

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