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

With no annotations, the description carries the full burden and does well: it discloses the resolution methods (IANA-routed RDAP, bounded TLS probe), the explicit handling of provider uncertainty, the cost ('$0.003 USDC per successful call'), and the privacy boundary. It omits auth requirements and rate-limit behavior, keeping it just below a 5.

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 sentences, each front-loaded and earning its place: capability, explicit exclusions, and pricing. No filler or redundancy.

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?

For a single-parameter tool with no output schema, the description adequately conveys the categories of state returned (registration, DNS, TLS, mail policy) and the cost model. It could go slightly further on return shape, but nothing essential to calling it correctly is missing.

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 the schema already fully documents the single 'domain' parameter (bare DNS name, not URL/path/IP/email). The description only restates 'bare public domain', adding no syntax or format detail beyond the schema. Baseline 3 is appropriate.

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 ('Resolve') and resource ('bare public domain') and enumerates the exact state domains returned: registration, DNS, HTTPS/TLS and mail-policy. This is clearly distinct from siblings like package_preflight (different resource) and api_discover, without needing to open any 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?

Strong negative scoping ('No registrant personal data, vulnerability scanning, mailbox existence or deliverability claim') tells the agent what this tool will NOT do, which implicitly routes those needs elsewhere. It does not name the specific sibling alternatives or state explicit when-to-use conditions, so it stops short of a 5.

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