Look Up Domain Registration

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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, but the description adds substantial context beyond them: redacted:true is the post-GDPR norm not a failure, the tool is observation-only with no record composed, pendingDelete/near-expiry must be reported not acted on, and 'unknown' means the registry did not answer rather than absence. It even explains what `reason` distinguishes (rate limit, timeout, registry error, no-RDAP TLD).

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?

It is dense and long for a one-parameter read tool, but it is front-loaded with the trigger and every clause carries behavioral payload (status semantics, unknown handling, redaction norm, advisory limits). Slightly more prose than strictly necessary, but no filler sentences.

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, so the description must carry the return-value burden, and it does: it enumerates the fields returned, defines the `status` enum values, and explains the `reason` field's meaning. An agent has everything needed to call it and interpret results, including the critical 'never say a name is free unless status is exactly not_registered' guard.

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% and the single `domain` parameter is fully documented in the schema (bare names, subdomains, no scheme/path/port, Unicode normalized to punycode). The description adds no parameter-level detail beyond that, so the baseline 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?

The description states a specific verb (read/look up) and resource (a domain's registration from the registry over RDAP) and enumerates exactly what it returns — registrar with IANA id, dates, EPP status codes, nameservers, DNSSEC signing, abuse contact. This is clearly distinguishable from siblings like get_domain_records or check_domain_verification, which concern DNS records and ownership proofs rather than registry registration data.

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?

It gives explicit trigger conditions framed as user questions (who owns it, when it expires, registrar/nameservers, is it registered, is a lock set) and labels the whole scope 'the WHOIS question', which is strong when-to-use guidance. It does not, however, name any sibling as the alternative or state when *not* to use it versus get_domain_records or check_domain_verification.

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