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

Annotations already declare readOnlyHint/openWorldHint/destructiveHint=false, and the description adds substantial non-obvious behavior on top: a checks map reporting which sections ran, were skipped or failed; partial-success semantics; the $0.03 USDC x402 payment path with supported chains and auto-pay clients; and the 'not charged when nothing is found' rule. This is exactly the operational context an agent needs before invoking a paid multi-source call.

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 purpose, then sources, then use cases, then input rules, then pricing/sample. Dense but each block earns its place; the pricing and free-sample sentences are longer than strictly necessary but they carry decision-relevant information for a paid tool.

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 return-shape burden and does so: key_facts as plain sentences, every section in full, plus a checks map. Input requirements, billing behavior, and failure/no-result semantics are all covered, leaving no material gap for correct invocation.

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, but the description adds a genuine cross-parameter constraint absent from the schema: zero parameters are required, yet at least one of name/vat_number/lei/domain must be supplied, and name+domain yields the fullest brief. That routing/combination guidance is real added value beyond the per-field descriptions.

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+resource ('Company check (KYB) and company enrichment in one call') and enumerates exactly what it aggregates: LEI legal entity, VIES VAT, OFAC/EU/UN sanctions, RDAP/email security, tech stack, news. It explicitly contrasts itself with the six sibling tools it replaces, so an agent can distinguish it without opening a 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 concrete use cases (supplier/customer onboarding, lead qualification, due diligence, sales research, especially European companies) and explicitly routes against alternatives by noting it is cheaper than calling company-lookup, vat-validate, sanctions-screen, domain-check, tech-stack and news-search one by one. It also states the input precondition (at least one of name/vat_number/lei/domain; name+domain gives the fullest brief) and the no-result billing exception.

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