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

With no annotations at all, the description carries the full burden. It implies a pure utility (format/parse/compare) but never states behavior such as expected input formats, error handling, or return shape. It also doesn't clarify whether the 'add' parameter is an operation selection or a value to add.

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 definition is brief and front-loaded, but it is under-specified rather than concise. A one-line category phrase cannot carry the needed information for a 3-parameter tool with dozens of overlapping siblings.

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?

For a generic name amid many highly specific date tools, the description does not provide enough context to disambiguate or to use the parameters. No output schema exists, so the description was the only source and it failed.

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 schema description coverage is nominally 100%, but each parameter description ('Add to process', 'Date to process', 'Unit to process') is a tautology. The tool description doesn't map its three verbs to the parameters, leaving an agent unable to construct correct arguments.

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 says 'format, parse, and compare' but does not state which of these this particular tool performs, nor how they relate to the 'add', 'date', and 'unit' parameters. It reads more like a category label than a specific operation, so an agent cannot tell it apart from the many sibling date tools like x402-format-date, x402-parse-date, or x402-add-days.

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 guidance is given on when to choose x402-date over any of the dozens of date-related siblings. There is no mention of alternatives, exclusions, or the conditions that select this tool.

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