validate_ico_number

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

Beyond the readOnlyHint=true annotation, the description discloses that validation is offline, based on modulo-11 checksum, and that it returns the normalized eight-digit form when valid. It also hints at the type of input errors it addresses (digit confusion in scanned documents), adding meaningful behavioral context.

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 description is compact, front-loaded with the most important purpose statement, and organized with clear Args/Returns sections. Every sentence adds value: purpose, use cases, parameter definition, and return behavior. No filler or repetition.

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?

Given the tool's low complexity (one parameter, output schema present, no nested objects), the description fully covers purpose, usage, behavior, and parameter semantics. The return value is summarized even though an output schema exists, and the offline/online distinction is highlighted.

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?

With 0% schema description coverage, the description compensates by defining 'ico' as 'A string that is supposed to be an IČO.' This adds semantic meaning beyond the bare string type, although it does not specify length or formatting constraints explicitly—those are mildly implied by the mention of a normalized eight-digit return.

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 description states a specific verb ('validate'), a precise resource ('IČO'), and the validation method ('modulo-11 checksum') while explicitly noting it does not call ARES. This distinguishes it from sibling tools like lookup_company and check_vat_registration without ambiguity.

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?

It provides clear usage context: 'a quick sanity check on form input or on a number read out of a scanned document, where 0/8 and 1/7 are routinely confused.' It does not explicitly name alternatives or state when not to use them, but the offline/no-ARES framing implies a lighter-weight verification than the sibling lookup tools.

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