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

No annotations are provided, so the description carries the full disclosure burden, and it discloses nothing: no timezone handling, no behavior when the date parameter is omitted (it is optional), and no return format. For a date-boundary utility with zero annotation coverage this is a complete transparency gap.

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?

Very short, but the brevity comes from under-specification rather than economy — the one sentence present is a verbatim repeat of the title and conveys no information, so nothing is front-loaded because nothing is said.

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 vague one-line description, an agent lacks everything needed to call this correctly: which date formats are accepted, whether the result is a timestamp or string, and how it relates to the many other date-boundary siblings are all unstated.

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 schema already documents it; per the baseline rule this is a 3. The description adds no format, timezone, or default-value meaning beyond what the schema provides.

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 'Start Of Day: Start Of Day' is a tautology that merely restates the tool name and title without stating a verb or what the tool actually computes or returns. An agent cannot tell from this text whether it returns a timestamp, a formatted date string, or a boundary object, nor how it differs from x402-end-of-day or x402-year-start.

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 when-to-use guidance, no prerequisites, and no mention of any alternative despite a dense sibling set (x402-end-of-day, x402-month-start, x402-year-start, x402-day-of-year) that an agent would need to disambiguate between.

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