eu_company_by_number

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

No annotations are provided, so the description carries the burden. It accurately conveys a read-only lookup action and clarifies supported countries and identifier types. However, it does not describe return behavior, error cases, or whether both Polish number formats are accepted interchangeably.

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 sentences with no filler, and the primary action is front-loaded. The only minor flaw is the slightly ambiguous pronoun 'it' in the second sentence, but the meaning is recoverable from context.

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 simple two-parameter lookup, the description provides enough context to invoke the tool correctly, including country-specific number types and a routing hint for Poland. It omits return-format details, but there is no output schema and the core usage is well covered.

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 the baseline is 3. The description adds meaningful context beyond the schema by explaining that 'number' means ICO in Czechia and NIP/REGON in Poland, and by giving concrete ISO examples for '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 ('Look a company up') and resource ('national registration number'), and clarifies the exact number types per country (ICO, NIP, REGON). It also differentiates from name-based search by noting that for Poland this is the only route.

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?

Gives clear context for when to use the tool: when a national registration number is available, and specifically for Poland since name search is not an option. It does not explicitly name the alternative tool for name-based lookup, but the guidance is strong enough for an agent to route correctly.

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