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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds what data is returned and the opt-in split-payment check, but says nothing about behavior on unknown VAT numbers, error shapes, or whether the lookup is live registry data.

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?

A single front-loaded sentence covering purpose, inputs and returned fields. The trailing HTTP route restates implementation detail that adds little for an agent, a small piece of non-earning content.

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?

There is no output schema, so the description carries the return-value burden and does so by naming the fields and the conditional split-payment result. Error/not-found behavior and data freshness remain undocumented, which is the main gap for a two-parameter lookup.

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% and both parameters are documented in-schema, so the baseline is 3. The description reinforces that 'id' is a VAT number and that check_split_payment is an additional check rather than a filter, but adds no format or validation detail beyond the schema.

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?

States a specific verb (look up / return registry data) and a specific resource (an Italian company identified by VAT number), and enumerates the returned fields (name, address, status). It does not explicitly contrast with the closely-named sibling acube_verify_fiscal_id, so sibling differentiation is left to inference.

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 'by VAT number' phrasing implies when to use it and the optional split-payment check is framed as opt-in, but there is no explicit when-to-use/when-not guidance and no routing away from acube_verify_fiscal_id or acube_get_recipient_code.

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