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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context beyond that: a per-success price ($0.005 USDC) settled via x402 on Base, which is a payment gate the annotations do not express, plus an explicit list of returned fields. It stops short of saying what happens on a no-match or payment failure.

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 English text is well front-loaded (purpose, then 'Use when', 'Returns', 'Price' labels), which is easy to scan. But the entire block is then repeated verbatim in Japanese, doubling length without adding information for an agent, and the 'Returns' section partly duplicates what the caller could infer from the response.

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 rightly enumerates the returned fields (corporate number, legal name/address, active/closed status, match evidence), and it discloses the paid-call model, so the main call-time questions are answered. The remaining gaps are the address-only mismatch with the schema's anyOf and the unspecified no-match behavior, which matter for a verification tool whose whole value is the negative case.

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 0%, so the description must carry parameter meaning; it covers three of the four inputs (name, 13-digit corporate number, address) but says nothing about response_language and its ja/en/both options, which the agent can only discover from the enum. It also implies address-only verification is possible, while the schema's anyOf requires name or corporate_number — a misleading signal about which argument combinations are valid.

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 first sentence names a specific verb (verify), a specific resource (Japanese company), the three accepted identifier types, and the authoritative source (NTA registry). This distinguishes it clearly from siblings such as jp_address_normalize or jp_business_card_extract, which handle adjacent but different resources.

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 'Use when: You need a Japanese company or corporate-number lookup' line gives clear positive selection context. However, it never names an alternative or exclusion — for example, whether jp_counterparty_check or jp_supplier_resolve should be preferred for risk/sanctions or vendor-onboarding flows — so the agent must infer boundaries from sibling names alone.

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