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

No annotations are provided and the description discloses no behavior, output format, side effects, or failure modes. The description carries the full burden and fails to say even whether this is a read-only lookup or a computation.

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?

Three words is not concise; it is under-specification. The repeated 'Domain Age' provides no information and no useful front-loaded content.

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 annotations, no output schema, and a tautological description, the definition is completely inadequate for correct invocation. Even for a potentially simple tool, an agent cannot determine inputs, semantics, or expected result.

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 100% coverage, but both parameter descriptions are generic boilerplate ('Input to process', 'Domain to process'), and the tool description adds no meaning. With two optional parameters ('input' vs 'domain'), an agent cannot tell which is expected, what format the domain should take, or why 'input' exists.

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 is 'Domain Age: Domain Age', a pure tautology that restates the tool name without a verb or resource. It does not state what the tool computes (e.g., registration age, days since creation) or how it differs from nearby siblings such as x402-domain-expiry, x402-age, or x402-age-calculate.

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 guidance on when to use this tool or which sibling to prefer. With dozens of domain/age-related siblings (x402-domain-expiry, x402-whois, x402-domain-audit, x402-age-calculate), an agent receives no decision criteria.

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