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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description adds substantial unstated-elsewhere context: $0.05 USDC per call via x402 on Base, the PAYMENT-SIGNATURE header requirement, the exact verdict vocabulary, and the Ed25519-signed receipt with key URL. It falls short of 5 because the receipt sentence is duplicated verbatim and the raw-HTTP payment instructions are awkward for an MCP caller, but the disclosure itself is genuinely rich.

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 well with the use case and decision output, but the entire receipt/public-key sentence appears twice word-for-word, wasting roughly a fifth of the text. The tail also drifts into raw endpoint and HTTP-header instructions that clutter the tool-call framing.

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?

Without an output schema, the description usefully pre-announces the return shape: action (allow/review/block), 0-100 risk score, corroborating registries, verdict enum and signed receipt. Coverage of sources and cost is thorough; only edge behavior (e.g. what not_found implies, latency/caching) is absent.

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 name, region and country are already documented. The description restates them ('Input: name, optional country (ISO-2) and region (WA, OR, QC)') and adds only the rationale that specific region codes unlock contractor-licence checks, which is already present in the schema. Baseline 3 is correct.

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 and resource ('verify' a 'business' for KYB) and immediately frames the decision output (allow/review/block plus risk score). It is clearly distinguishable from enrichment siblings like company_enrich or the narrow qc_contractor_check, since it names the registries and sanctions lists it corroborates against.

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?

'Call before paying, onboarding or contracting a company' gives an explicit trigger context, and 'Businesses only' sets a scope exclusion. It does not name alternatives or say when to prefer a sibling (e.g. qc_licence for a single licence lookup instead of a full KYB verdict), so the routing guidance stops short of 5.

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