インボイス登録番号を検証

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

With no annotations, the description fully discloses behavioral traits: it explains that corporate numbers get mathematical check-digit verification, individual numbers only get format validation due to unpublished check-digit methods, and it explicitly disclaims existence/validity guarantees. This is exemplary transparency.

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 three sentences long, front-loaded with the main action ('形式を検証します'), and each sentence adds meaningful detail about the validation logic or limitations. There is no redundancy or filler.

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?

The description thoroughly covers the input format, validation behavior for both entity types, and the tool's limitations, which is substantial given the simple single-parameter tool. However, because there is no output schema, the description could optionally mention the return value (e.g., boolean), which is a minor gap.

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 for the single parameter is 100%, with the schema already describing the format ('T'+数字13桁) and allowed full-width/hyphen/space characters. The description adds no new parameter-level semantics beyond reinforcing the structure, which is already fully documented in the schema.

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 opens with a specific verb '検証します' targeting the '適格請求書発行事業者の登録番号("T"+数字13桁)', clearly identifying the resource. It distinguishes from sibling validate_corporate_number by focusing on invoice registration numbers and even differentiates between corporate and individual number validation.

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?

The description gives clear context for when to use the tool: it validates formats, and for corporate numbers also performs check-digit verification. It explicitly states when not to rely on it ('実在確認・登録の有効性は保証しません') and directs users to the official NTA site for existence confirmation, providing a clear boundary without naming sibling tools.

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