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

With no annotations, the description carries the full burden, and it does disclose per-input return content (registrar, created/expiry, status, nameservers, DNSSEC; network range, org, country, abuse contact). It omits operational behavior such as rate limiting, lookup failures for unregistered domains, or RDAP server coverage. For a low-risk public read, this is solid but not exhaustive.

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?

A single front-loaded sentence with the resource type stated first and the parenthetical field lists carrying dense, non-redundant detail. No filler or repetition.

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 only one parameter, no annotations, and no output schema, the description's enumeration of returned fields is what makes the tool usable without a return schema. It is nearly complete, losing only on unsupported-lookup or rate-limit behavior.

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?

One parameter with 100% schema description coverage, so the schema already documents that 'query' accepts a domain, IPv4/IPv6, or ASN with the AS13335 example. The description restates this same information rather than adding format constraints or normalization rules, so it adds little beyond the schema.

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?

The description names a specific verb (WHOIS via RDAP) and enumerates the three resource types it accepts and the exact fields it returns for each, so the purpose is unambiguous. It does not, however, reference any sibling tool (e.g. lookup_ip, reverse_dns, dns_lookup), so an agent must infer the boundary from the RDAP field list alone.

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?

Usage is only implied: the accepted input forms (domain, IP, ASN) suggest when the tool applies, but there is no explicit statement of when to prefer it over lookup_ip or dns_lookup, and no mention of exclusions or prerequisites. No guidance on invalid input or unsupported TLDs either.

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