Current WHOIS

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds context about the returned fields and the 'where not redacted' caveat, which is useful but minimal. It does not cover rate limits, auth, or error behavior, though those are less critical given the annotations.

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?

The description is a single, front-loaded sentence that immediately states the action and resource, then lists the expected output fields. No filler or repetition. It earns the maximum for efficiency.

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?

Given the tool's simplicity (2 params, no output schema) and the annotations covering safety, the description is nearly complete. It lists the main data categories returned, mentions redaction, and differentiates current vs historical. It lacks explicit error/not-found handling, but that is a minor gap for a lookup tool of this nature.

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%: both parameters have detailed descriptions (domain pattern and response_format enum). The description text itself does not add extra meaning beyond what the schema provides, so the baseline of 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?

The description states a specific verb ('Fetch'), a specific resource ('current WHOIS record'), and enumerates the key data fields (registrar, registrant contacts, nameservers, dates). It clearly distinguishes from siblings like whois_history (historical) and ip_whois (IP-based) by the word 'current'.

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?

The description implies a current-data use case but does not explicitly contrast with alternatives. It says 'current WHOIS' which hints at the historical sibling, but it never names when-not-to-use or other conditions (e.g., for full domain details use domain_details). The guidance is adequate but not explicit.

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