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

No annotations exist, so the description carries the burden. It usefully discloses the default-to-today behavior and the paywall context ('5 free trial calls per signed wallet'), but says nothing about accepted date formats or what happens on invalid input. Adding the default value is real value beyond structured fields.

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?

One compact sentence that front-loads the computation and ends with the default behavior; nothing is wasted except the emoji/pricing tail, which is noise for tool selection.

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 single-parameter computation with no output schema or annotations, the description covers what is computed and the default. It is missing the input date format and any hint of the return shape (week number plus ISO year), which are the only meaningful gaps.

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 0%, so the description must compensate. It does clarify that 'date' is optional and defaults to the current date, which the bare schema does not, but it never specifies the expected string format (e.g. YYYY-MM-DD), leaving the single parameter only partially documented.

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?

States a specific verb (computes) and resource (ISO week number and ISO year) scoped to a given date. It implies ISO semantics but never names the close siblings like x402-week-of-year, x402-iso-week, or x402-calendar-weeks, so an agent gets a clear purpose without explicit disambiguation.

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?

The description conveys implied usage: pass a date, or omit it to get the current ISO week. It gives no when-to-use versus the many week/date siblings, no exclusions, and no routing guidance, leaving the agent to infer the appropriate context.

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