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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered. The description adds what the response contains and the 1-10 domain batching, which is useful context, but says nothing about per-domain failure behavior, rate limits, or data staleness for a network-backed lookup.

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 that leads with the data source and then the payload, with zero filler. Every element earns its place in the definition.

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 no output schema, the description correctly compensates by enumerating the return fields, and it states the batch bounds. Only the per-domain error/failure semantics are missing, which is a minor gap for a simple read-only lookup.

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?

There is a single parameter with 0% schema description coverage, and the description only restates the cardinality constraint (1-10 domains) that the schema already enforces via minItems/maxItems. No format guidance is given (whether inputs need schemes, subdomains, IDN handling), so it does not compensate for the undocumented parameter.

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 the resource (RDAP registration data) and enumerates the returned fields (registrar, created, updated, expires, age, status), so an agent can tell it retrieves WHOIS-style registration details. It is a noun phrase rather than an explicit verb, and it does not distinguish itself from the sibling domain_report, which likely overlaps.

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?

There is no statement of when to use this tool versus domain_report, email_security, or tech_stack, and no prerequisites or exclusions are given. The only usage signal is the batch size limit, which is not the same as routing guidance.

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