法人番号・T番号から会社情報を調べる

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

Annotations already declare read-only, idempotent and non-destructive behaviour, yet the description still adds real value: input normalization rules (hyphens, spaces, full-width digits), the exact fields returned, active/closed status, and the four possible invoice registration states. It also discloses sole-proprietor behaviour and the cost ('uses 1 API request'), which is useful quota context an agent cannot get from annotations.

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 description is front-loaded with the identity of the tool and accepted input formats, and each sentence carries distinct information (formats, returns, sole-proprietor caveat, fallback sibling, cost). It is dense with Japanese parentheticals, but nothing is genuinely 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?

With no output schema, the description compensates by enumerating the returned fields and the possible invoice status values. For a two-parameter read tool with full annotation coverage, an agent has everything needed to call it correctly and interpret the result.

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 goes further by showing a concrete formatted example and confirming that punctuation and full-width characters are tolerated — details the schema does not state. It does not explain the response_format parameter, though the schema documents that adequately.

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 names a specific verb (look up) and resource (one Japanese company or invoice issuer) and states the two exact key formats it accepts. It is readily distinguishable from bango_find_company, which it explicitly identifies as the name-based alternative.

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 states the input condition (you have a corporate number or T-number) and explicitly redirects to bango_find_company when only a company name is available. It does not clarify its relationship to bango_check_invoice, which also deals with invoice registration status, leaving one sibling overlap unresolved.

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