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

With no annotations provided, the description carries the full burden. It discloses the cost ($0.02 per call via x402), and states it resolves from authoritative registries, making it reliable for .nl and EU ccTLDs. It does not mention rate limits or auth, but the behavior is well-described for a simple read operation.

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 concise and well-structured, with key information front-loaded (purpose, cost, what it returns). Every sentence adds value; no fluff or repetition.

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 simple single-parameter tool with no output schema or annotations, the description covers the core functionality, data returned, cost, and use case. It lacks error handling or example responses, but is sufficiently complete for an agent to understand the tool's purpose and output.

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?

The input schema has one parameter 'domain' with a description. Schema coverage is 100%, so the description adds little beyond what the schema already provides. The description restates the parameter's purpose but does not add new semantic information.

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 purpose: to look up a domain's registration and age via RDAP. It lists the specific data returned (registration date, age, registrar, etc.) and distinguishes it from sibling tools like dns or enrich by focusing on registration info.

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 mentions the tool is useful for lead qualification and trust scoring, implying when to use it, but it does not explicitly state when not to use it or compare it to alternatives like dns or enrich. No exclusions or alternative guidance is provided.

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