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

With no annotations, the description must carry behavioral disclosure. It usefully specifies the output format and gives an example, but it does not clarify what happens when date is omitted, which input formats are accepted, or whether output is always UTC versus preserving a local offset.

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?

Two sentences, no filler. The standard and example are front-loaded, and the optional-date note is the only added usage information. Every word earns its place.

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 simple one-paramer, no-output-schema tool, the description is minimally viable but has meaningful gaps: no default behavior when date is omitted, no accepted input formats, and no explicit timezone guarantee beyond the 'Z' example. An agent could still call it, but not fully predict edge-case behavior.

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 description coverage is 100% for the single date parameter, so the baseline is 3. The description adds that the date is optional, but it does not clarify the accepted date format or the meaning of 'Date to process' beyond the schema's own vague wording.

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 names a specific action (format), a resource (a date), and an exact output contract (RFC 3339 timestamp with an example). It is clear enough to be distinguished from nearby date tools like rfc2822, though it does not explicitly name any sibling or exclusion.

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 about when to choose this tool over alternatives such as x402-rfc2822, x402-format-date, or x402-parse-date. The only usage hint is 'Provide optional date,' which describes input rather than selection context.

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