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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, and the description adds context they cannot carry: no account is required, and critically that a null field means WITHHELD or not measured rather than clean. That null-semantics warning is the kind of behavioral disclosure an agent would otherwise misread as a negative result.

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?

Three tight sentences: purpose, alternative, and the null-field caveat, in that order. Nothing is repeated and every clause earns its place, with the most decision-relevant content front-loaded.

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?

An output schema exists, so return shape needn't be explained; instead the description covers the one thing the schema can't — how to interpret null fields. Purpose, alternative routing, auth precondition, and result interpretation are all present for a two-parameter read-only tool.

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% — both ico and country are thoroughly documented, including normalization and country tie-break behavior — so the schema does the heavy lifting and baseline 3 applies. The description adds no parameter-level detail beyond what the schema already provides.

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 resource (public compliance snapshot for one company) and enumerates the exact data domains returned: sanctions screening, insolvency, debtor registers, VAT reliability. It explicitly contrasts itself with the sibling kyb_check ('lightweight' vs 'full KYB picture'), so an agent can distinguish it without opening either schema.

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?

Names the alternative (kyb_check) and the condition that selects it (need for the full KYB picture), plus a usage precondition ('works without an account'). It stops short of explicit when-not-to-use guidance for the other ten siblings, but the core routing decision is unambiguous.

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