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

Annotations declare readOnlyHint=false and openWorldHint=true; the description explains the non-obvious reason — a verification record is persisted, so it is not a pure read ("Stored as a verification record (see get_record)"). It also discloses a credit cost, a genuine behavioral trait not present in any annotation. It stops short of describing latency, failure modes, or what a returned result looks like.

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?

Front-loaded with the action and the country-specific sources, then the storage and cost facts. Dense and largely waste-free, though the telegraphic phrasing ("§81 list", "published accounts") assumes domain fluency and the two trailing clauses read as afterthoughts.

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 carries the burden of saying what happens on return, and it does so by pointing to the persisted verification record via get_record. Cost and per-country coverage are covered; an agent still lacks a sense of what a verdict looks like or how long the live lookup takes.

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 reinforces the country scope (SK/CZ/RO) that matches the enum, but adds nothing about regNo format or the date/account parameters beyond what the schema already documents.

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 specific action (live VAT risk check) and enumerates the exact per-country sources consulted: SK §81 list, CZ unreliable VAT payer (§109), RO inactive taxpayer. That is far more concrete than its siblings get_risk or verify_company, though it never explicitly distinguishes itself from them.

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?

"Before paying a supplier" gives a clear situational trigger for when to call it, and "Costs credits" hints that it should not be called casually. However, it never states when NOT to use it or why an agent would pick this over verify_company or get_risk, which occupy adjacent territory.

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