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

Annotations already establish readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds genuinely useful context beyond that: the rules year and last-updated date, the source page URL, the returned structure (result rows, raw engine outputs, sources with lastChecked dates, disclaimer) and the output language. It stops short of richer disclosure, but for a pure computation tool this is solid.

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 core purpose is front-loaded in the first sentence, with versioning, URL and return-shape details following. The prose is dense but every clause carries information; only the trailing 'Only used when' note is dead weight because no such marker exists in this schema.

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?

With no output schema, the description takes on the burden of describing returns, and it does so (result rows, raw engine outputs, sources with lastChecked dates, disclaimer) as well as naming the year and rules version. Required inputs and the emission-category enum are covered by the schema, so the only residual gap is the mismatched conditional-input note.

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 hrubaMzda, inputPrice and emisniKategorie are already fully documented, including the emission-category enum values and their rates. The description restates the rate-by-emission-category mapping but adds no syntax, format, or dependency detail beyond the schema. The closing note about 'Only used when' inputs references a marker that does not appear in this schema, so it adds no usable parameter meaning here.

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 names a very specific resource — the Czech taxable benefit for private use of a company car for 2026 — and even enumerates the applicable rates (1 %, 0.5 %, 0.25 %) and what the output expresses (monthly increase in tax advance plus social/health insurance). Sibling tools are all different country/benefit calculators, so differentiation is implicit in the country+benefit naming rather than stated. It lacks an explicit verb but is otherwise unmistakable.

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?

No explicit when-to-use, when-not-to-use, or alternative-routing sentence is present; the usage is only implied by the highly specific computation described. Because every sibling is a distinct country/benefit calculator, there is little ambiguity to resolve, but the description still does not tell the agent when this tool is the right pick.

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