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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds the default-resolution rule for the main VAT-payer company, which is genuinely useful behavioral context, but says nothing about what the listing contains or how year scoping affects results.

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 compact sentences, front-loaded with what is returned and followed by the scoping default. No filler; the only cost is that terseness comes at the expense of detail.

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 should hint at the return shape and at how 'year' filters results, and it does neither. For a two-parameter listing tool it is minimally adequate, but leaves real gaps an agent must guess at.

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 50%: companyId is documented in the schema and reinforced by the description's default rule, but the 'year' parameter is unexplained in both places. The description partially compensates for the coverage gap on companyId but leaves year's filtering semantics entirely to inference.

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 uses a specific verb ('Drive vygenerovana' = lists previously generated) plus a precise resource (VAT filings) and even enumerates the subtypes (priznani, kontrolni a souhrnne hlaseni). It implicitly contrasts with the singular get_vat_filing and with generate_vat_filing, though it never names those siblings explicitly.

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 gives one useful conditional: omit companyId and the main company is used if it is a VAT payer. But it never says when to prefer this list tool over get_vat_filing (single) or generate_vat_filing, nor any prerequisites, so usage is only implied.

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