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

No annotations are supplied, so the description carries the full disclosure burden. It does add a genuinely useful non-obvious trait: the tool is paid ($0.005 per call, USDC on Base), which an agent needs before invoking. However, it says nothing about determinism, invalid-date handling (e.g., Feb 30), or timezone assumptions.

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?

A single tight sentence that front-loads the purpose, then the output fields, then the pricing. Nothing is redundant and no sentence fails to earn 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?

With no output schema and no annotations, the description compensates well by listing all returned fields and disclosing the payment model. The remaining gap is input validity behavior and parameter conventions, which leaves it just short of fully self-contained.

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 0% for three required numeric parameters, and the description adds no format or range detail beyond implying they form a calendar date. An agent cannot tell from the text whether month is 1-12 or a name, or whether day is 1-31, so the description does not compensate for the coverage gap.

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 gives a specific verb and resource ('Describe a calendar date') and enumerates the exact outputs (weekday, ISO week, day of year, quarter, leap year, weekend), which makes the tool's function unambiguous. It does not explicitly contrast itself with the nearest sibling tk_businessDays, but the listed return fields make the boundary inferable.

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 explicit when-to-use or when-not-to-use statement and no named alternative. Usage is only implied by the enumerated output fields, which suggest the tool is for deriving calendar metadata from a date. Adequate for a simple pure-computation utility, but no routing guidance is provided.

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