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

Beyond the readOnly/openWorld annotations it discloses paid-call mechanics ($0.002 USDC per successful call via x402 on Base/Solana/Arc) and, importantly, that failed calls are not charged — a material detail for an agent deciding to invoke. It also adds data provenance and refresh cadence (free weekly bulk files) and coverage boundaries, which the annotations cannot express.

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?

Front-loaded with the identity of the record and its source, then the field list, then the pricing caveat. The field enumeration is long but each item is a distinct output field an agent may need; only minor tightening is possible.

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 single-parameter lookup with an output schema and readOnly/openWorld annotations, the description supplies everything else that matters: data source, update cadence, population size, exclusion of sole traders, and the billing model including no charge on failure.

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%, and the schema already specifies 10 digits with an example. The description restates the identifier name and digit count but adds no further syntax normalization or format rules, 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 verb+resource: a Swedish company register record looked up by 10-digit organisation number, sourced from Bolagsverket/SCB. It enumerates the returned fields and scopes coverage (2.2M companies/associations, sole traders excluded), which clearly separates it from the many other national company-register siblings such as b2b_brreg_norway_companies or b2b_ireland_cro_companies.

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 lookup key (10-digit organisationsnummer) and the exclusion of sole traders give a clear usage context and one negative constraint. It does not explicitly route the agent away from sibling registers for other jurisdictions, but the country and identifier format make the intended use unambiguous.

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