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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuine context beyond that: which national registries back each country and the lt fallback behavior to VIES/GLEIF. It omits not-found/error behavior and auth expectations, but adds real value over the annotations.

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 purpose followed by a dense but earned country-to-ID-type list; there is no filler. The enumeration is long but every entry carries lookup-relevant information.

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 multi-registry open-world lookup with no output schema, the description supplies the supported countries, their ID formats, and a fallback rule, which is enough to call it correctly. It stops short of describing return shape or miss/error handling, a minor remaining 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%, so baseline is 3. The description goes beyond the schema by mapping each country to the specific expected ID type (CRN, IČO, KRS, SIREN, CVR, etc.), which materially clarifies what the id parameter should contain for a given country.

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 (Get) and resource (company), plus a precise scope: non-Czech companies looked up by national ID and country code. The country/ID-type enumeration makes it clearly distinguishable from search_company and lookup_company_by_vat.

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?

Provides rich per-country support context and a concrete fallback rule for lt (VIES/GLEIF when the local store is unavailable or has no match), which implies the lookup path. However, it never explicitly states when to prefer this over the sibling lookup_company_by_vat or search_company, leaving the routing to inference.

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