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

No annotations are provided, so the description carries the full burden. It claims the data is 'Authoritative' and from the RZP register, but does not disclose behavioral traits beyond the schema, such as read-only nature, error handling, or rate limits. The batch limit (up to 20) is already in the schema, so the description adds minimal 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 two sentences, with the core purpose and output fields front-loaded, followed by usage context. There is no redundant wording, making it efficient and easy to parse.

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 single-parameter tool with no output schema, the description lists the output fields (payer yes/no, effective from, tax office, trade licences) and the register source, which helps an agent understand the response. It lacks details like error handling or rate limits, but those are less critical for a read-only status check.

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 the baseline is 3. The description repeats the batch limit (up to 20) which is already in the schema, but adds no extra meaning about the ids parameter beyond what the schema provides.

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 title and description clearly state the tool's purpose: checking Czech VAT (DPH) status. The description specifies the resource (RZP register) and the exact data returned (payer yes/no, effective from, tax office, trade licences). This distinguishes it from siblings like entity_status or company_lookup, which are broader in scope.

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 description provides a clear use case: 'Use before issuing/czech invoicing.' However, it does not explicitly state when not to use the tool or mention alternatives among the sibling tools, such as company_lookup for general company information. This gives context but lacks exclusions.

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