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

No annotations exist, so the description must carry the behavioral disclosure burden. It only says 'Calculate age' and does not mention what the output looks like, whether the result is in whole years, whether it uses the current date as the reference, how leap years are handled, or what date formats are accepted. The tool's safety profile is also unspecified.

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 short and front-loaded, using one sentence with no filler. The leading 'Age:' prefix is slightly redundant with the tool name, but the overall structure is efficient and easy to scan.

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 tool is simple, but with no output schema and no annotations, the description should explain the return value and input requirements. It does not state whether age is returned as years, days, or an object, nor what date formats are valid. Given the existence of x402-age-calculate, more detail is needed for an agent to confidently invoke this tool.

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 coverage is 100%, so the baseline is 3. The description adds mild value by clarifying that 'dob' means date of birth, but it does not specify the acceptable format (e.g., YYYY-MM-DD), timezone handling, or validation behavior. The schema's 'Dob to process' is itself vague.

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 uses a clear verb-resource pair: 'Calculate age from a date of birth.' It states exactly what the tool computes. However, it does not distinguish itself from the nearly identical sibling x402-age-calculate, so an agent cannot tell which one to prefer.

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 about when to use this tool versus alternatives. With hundreds of siblings, including x402-age-calculate and x402-account-age, the absence of any exclusion or routing hint leaves the agent to guess. No prerequisites, date-format expectations, or alternative suggestions are provided.

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