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

With no annotations, the description carries the full behavioral burden. It does add real value by disclosing what is returned: all facility fields (address, phone, departments, coordinates) plus conditional hours and hours_snapshot when schedule data exists. It does not state what happens when the code matches no facility (empty result vs error), nor whether the call is a pure read with any rate limits.

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 identifier and the result shape, with no filler. The second sentence about conditional hours data is well placed, though slightly dense with parenthetical field names.

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 single-parameter lookup with no output schema, the description is nearly complete: it explains the return payload, including the conditionally present hours/hours_snapshot. The only meaningful gap is not-found behavior, which matters for an agent deciding how to handle a miss.

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?

There is only one parameter, and schema coverage is 100%: the schema already documents the 10-digit pattern, the example 1310110049, and the medical-institution-code semantics. The description only repeats the '10-digit code' constraint, so it adds no meaning beyond the schema and the baseline 3 applies.

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?

The description states a specific verb (取得) and resource (施設の全項目) along with the precise key (10桁の医療機関コード) and scope (1件取得). This clearly separates it from the sibling search_facilities/search_nearby tools, which return sets rather than a single record identified by code.

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?

Requiring a known 10-digit code implicitly signals that this is a direct-lookup tool rather than a discovery tool, but the description never names the alternatives (search_facilities, search_nearby, analyze_trade_area) or states the condition that selects them. The agent has to infer when to use this versus the search siblings.

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