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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds domain meaning about what the check certifies, but does not state what the response looks like (boolean result, issuer name, not-found handling), which matters since there is no output schema.

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 short sentences, front-loaded with the purpose and followed by the accepted input formats. No filler, though the parenthetical rationale slightly interrupts the flow of the primary statement.

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 one-parameter read-only lookup this is nearly complete: purpose, business rationale and input formats are all present. The only shortfall is that no return-value behavior is described and no output schema exists to fill that 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 is 100% and the schema already documents the single 'number' parameter with an example format. The description restates the accepted formats (T + 13 digits or the 13-digit corporate number), confirming that the T prefix is optional, which is a marginal clarification rather than new 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?

States a specific verb and resource – checking whether a Japanese corporation is a registered Qualified Invoice Issuer – and frames the business meaning (consumption-tax credit). This is clearly distinct from sibling tools such as search_company or get_company_profile, which deal with company data rather than invoice registration status.

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 a clear context for use: verifying Qualified Invoice Issuer status when consumption-tax credit is at stake. It does not name alternatives or state when-not to use it, but for such a narrow, single-purpose lookup the implied usage is unambiguous.

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