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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds the traits that actually cause misevaluation: coverage varies by country, `checks[]` is tri-state (hit/clear/not_covered), and `overall = INSUFFICIENT_DATA` is explicitly NOT a clean result. The null-field caveat (WITHHELD or NOT MEASURED, not clean) is exactly the kind of trap disclosure annotations cannot carry.

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 correctly: purpose and scope first, usage trigger second, interpretation caveats last. Every sentence carries information, but the final third explains output-field semantics (`checks[]`, `overall`, nulls) that partially overlap with the available output schema, so it is slightly longer than strictly necessary.

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?

Given rich annotations, a full output schema and 100% parameter coverage, the remaining burden is interpretive risk guidance — and the description supplies the two failure modes (country-coverage gaps and null-vs-clear confusion) that would otherwise cause the agent to report a false clean bill of health.

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 `ico`, `country` and `purpose` are already fully documented, including the cross-country identifier collision and the enum licensing constraint. The description adds nothing about input parameters — its references to `checks[]` and `overall` are output fields — so the baseline 3 applies.

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 concrete artifact ('One-call Know-Your-Business summary for one company') and then enumerates exactly what the summary contains: registry status, insolvency, liquidation, sanctions, debarment, tax/social/health debts, VAT reliability and an overall verdict. That enumerated scope cleanly separates it from broader siblings like get_company_details, company_brief or check_compliance without needing to name 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?

It gives an explicit trigger ('Use before onboarding a customer or supplier') and adds a reporting instruction ('say so when you report it'). It stops short of naming when to prefer an alternative sibling (e.g. check_compliance) or when not to use it, so it is clear context rather than full routing guidance.

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