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

Annotations already cover read-only, idempotent, non-destructive, closed-world behavior. The description adds useful behavioral context beyond that: it returns compact rows, points to get_facility for richer details, and explains that null means unpublished (要問合せ), never 0.

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 tightly written sentences with no wasted words. The core search purpose and the get_facility routing are front-loaded, and the null caveat is compactly appended.

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 12-parameter search tool with full schema coverage and annotations, the description provides what an agent needs: search scope, result nature ('compact rows'), where deeper detail lives, and how to interpret nulls. No output schema is present, but the description sufficiently covers return expectations.

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 fully documents all 12 parameters. The description reinforces several filter concepts but does not add syntax or constraints beyond the schema; the null explanation is return-value semantics rather than parameter meaning.

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 uses a specific verb ('Find') and resource ('private after-school care facilities in Tokyo') and enumerates the filtering dimensions. It also distinguishes itself from get_facility by saying detailed fee conditions, pickup schools, and application routes live there.

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 clearly indicates when to use this tool: searching facilities by ward, feature, pickup school, fee ceiling, closing time, and more. It explicitly routes users to get_facility for detailed data, though it does not contrast itself with the generic search or list_wards siblings.

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