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

Annotations cover only readOnlyHint and openWorldHint, but the description adds decisive behavioral context the annotations lack: the $0.003 USDC per-successful-call price, the x402 payment rails (Base, Solana, Arc), and that failed calls are not charged. That payment/charging disclosure is essential operational context for an agent.

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?

Dense but well front-loaded: countries and search modes come first, then return fields, sibling routing and pricing. Slight redundancy with the schema on ID formats costs a point, but nothing is wasted.

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 an output schema present, the description needn't detail return values, yet it still summarizes them; it covers country coverage, search vs. lookup modes, the Poland restriction, sibling routing for France, and the payment model. Nothing an agent needs to invoke it correctly is missing.

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 both q and id formats are already fully documented in the schema. The description largely restates those formats (Norway 9 digits, Y-tunnus, IČO, KRS) rather than adding new meaning, so the baseline 3 applies.

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 resource (official company registers) and scopes it precisely to Norway, Finland, Czech Republic and Poland, which cleanly distinguishes it from sibling tools like company_fr, company_br, uk_company and lei. An agent can immediately tell what this tool covers and what it does not.

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?

Explicitly states the two usage modes (search by name for Norway/Finland/Czech; look up by number for all four), flags the constraint that Poland is number-only, and routes France to /api/company/fr. The when-to-use conditions and the alternative are both named.

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