APIbase

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

With no annotations provided, the description carries the full burden and adds valuable context by identifying the data provider '(WhoisXML)' and implying bulk results ('Find all domains'). However, it omits critical behavioral details like rate limits, authentication requirements, or GDPR/privacy constraints typical of WHOIS data.

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, efficiently structured sentence that front-loads the core action, specifies the search targets, identifies the mechanism (reverse WHOIS), lists use cases, and cites the provider—every clause earns its place with zero 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 simple single-parameter lookup tool without an output schema, the description adequately covers selection criteria (what it does, what input it expects, and the provider). It could improve by hinting at the return format (list of domains), but remains sufficiently complete for tool selection.

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?

Given 100% schema description coverage where the 'keyword' parameter is already well-documented with examples ('John Smith', 'acme.com'), the description reinforces the semantic meaning (registrant details) but adds no additional syntax, validation rules, or format specifications 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 states a specific action ('Find all domains') and target resource ('registered by a person, company, or email'), clearly distinguishing this from sibling tools via the explicit 'reverse WHOIS lookup' label—differentiating it from forward lookup tools like whois.domain.lookup.

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 provides clear context for when to use the tool by citing specific use cases ('OSINT and brand monitoring') and implying the data flow direction (registrant info → domains). However, it lacks explicit 'when not to use' guidance or named alternative tools for forward lookups.

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