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

With no annotations supplied, the description carries the full burden, and it does disclose meaningful behavior: timezone is explicitly Japan time, open_now and day/time act as mutually distinct narrowing modes, and the response includes weekday hours with null for facilities lacking data. It omits result ordering and pagination/offset behavior beyond the limit parameter, so it is not fully complete.

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?

The sentences are ordered from overall scope to preconditions to filtering modes to return values, and the core scope statement comes first. There is mild redundancy where open_now and day/time semantics partly restate the schema descriptions, but no sentence is wasted.

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 7-parameter search with no output schema and no annotations, the description covers filtering and filter preconditions well and partly describes the return payload (hours, nullable). It does not describe the rest of the facility record returned or how limit interacts with large result sets, which an agent would need to know to plan a search.

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 the baseline is 3, but the description adds the cross-parameter constraint that query or prefecture must be present, which the schema does not state anywhere. It also reinforces that day and time are meant to be combined and that open_now uses JST, adding meaning beyond the field-level text.

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 gives a concrete verb (検索) and resource (全国の薬局・医科・歯科医療機関) plus the filterable facets, so an agent can tell this is the keyword/attribute search over the facility database. It does not explicitly name get_facility or search_nearby as the alternatives, so sibling differentiation is implicit rather than stated.

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 states a real precondition ('query と prefecture の少なくとも一方が必要です') and explains the open_now and day+time filters, which guides invocation. However, it never says when to choose this over search_nearby (geo search) or get_facility (single-record lookup), leaving the sibling choice to inference.

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