domain_lookup

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

With no annotations, the burden falls on the description. It discloses the use of RDAP and WHOIS and the type of information returned, which is useful. However, it doesn't describe error behavior (e.g., what happens if RDAP and WHOIS both fail), rate limits, or the raw response structure, leaving some behavioral uncertainty.

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 compact two-sentence summary that front-loads the primary action and then lists key result categories. No redundant phrases or filler.

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?

The description covers the tool's core purpose and the main data categories returned, which is sufficient for a three-parameter lookup tool. It falls short of explaining potential failure modes or the exact shape of the output, but given the absence of an output schema and the simplicity of the operation, this is a minor gap.

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?

All three parameters are well-described in the schema (domain, include_raw, prefer_whois) with clear documentation. The description adds context by explaining the fallback mechanism, which indirectly clarifies the purpose of prefer_whois, but this is marginal beyond the schema. Since schema coverage is 100%, 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 clearly states the function with the verb 'Look up' and specifies the resource as 'domain information.' It distinguishes the method by naming RDAP and WHOIS fallback, and lists the types of details returned (registration, nameservers, contacts, status). This is specific and aligns with the tool name.

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?

No explicit usage guidance is provided. There are no sibling tools to compare with, and the description doesn't state when to choose this tool over alternatives or when not to use it. The context implies it's for domain lookups, but the fallback behavior and parameter options (include_raw, prefer_whois) are not framed as decision points.

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