WHOIS Reverse Lookup

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

Annotations declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true. The description adds behavioral traits beyond these: pagination details, default vs mini mode, and parameter-specific matching behavior. No contradiction exists.

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 four sentences with zero wasted words. It front-loads the main purpose, then sequentially adds essential details: parameter constraints, search methods, and pagination behavior. Every sentence earns its place.

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 no output schema, the description covers pagination, two result modes, and parameter constraints. It lacks explicit mention of output format or auth requirements, but annotations already indicate read-only and idempotent behavior, reducing the need. For a tool with 7 parameters and pagination, the description is largely complete.

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%, so baseline is 3. The description adds extra meaning: 'keyword uses pattern matching, email supports wildcard regex (e.g. 'm*@gmail.com'), owner and company use full-text phrase matching.' It also explains mode and exact parameters in more functional terms than the schema's 'description' fields.

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 clearly states the tool's verb ('Search') and resource ('WHOIS records in reverse'). It specifies the goal: 'find all domains linked to an owner, email, company, or keyword.' This distinguishes it from siblings like 'whois_domain_lookup' or 'whois_bulk_domain_lookup' by emphasizing reverse 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?

The description explicitly instructs the agent to 'Provide exactly one of: keyword, email, owner, or company.' It details the search behavior for each parameter (pattern matching, wildcard regex, full-text phrase matching). While it doesn't explicitly state when NOT to use this tool or list alternatives, the sibling tool names and context make the usage fairly clear.

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