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

With no annotations, the description carries the full burden and does so: it discloses the exact evidence gathered (RDAP domain age/registrar, DNS A/MX/NS, SPF/DMARC, HTTPS), the return shape (verdict plus 0-100 trust score with evidence URLs), the flagged risk pattern, and the operational constraints (free tier unsigned and rate-limited, $0.05 USDC for signed/no-limit, payment header names, transport parity).

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 the core question and purpose, and most sentences earn their place. Some redundancy exists: the standalone fragment 'Signed attestation.' plus the later full signed-attestation/payment paragraph and 'Same price on either transport' overlap slightly, costing some tightness.

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, and the description compensates by describing the verdict, trust score range and evidence URLs returned. Combined with the payment/auth tiering and rate-limit notes, an agent has everything needed to call this correctly in a single domain argument.

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?

Only one parameter and the schema already documents it at 100% coverage ('Domain to verify, e.g. example.com'). The description never adds domain-specific syntax (subdomains, IDN, scheme handling) beyond what the schema states, so the baseline of 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?

States a specific verb and resource ('Is this company or domain legit? Business and domain verification (KYB)') with concrete scope: vendor screening, supplier checks, scam/fraud review. This is clearly distinct from the sibling tools verify_claim, verify_freshness and verify_price, so an agent can route correctly without opening the 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?

Gives explicit triggering moments ('Use it before your agent pays an invoice, onboards a vendor or trusts a site') and names alternatives for adjacent needs: the batch endpoint for bulk and the paid x402/HTTP path for signed attestations. When-to-use and the alternative paths are both spelled out.

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