Date math: durations & business days (paid $0.001)

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

With no annotations provided, the description carries the transparency burden. It discloses the paywall behavior (x402 challenge) and that x_payment is required to settle the $0.001 fee, along with configurable weekend/holiday handling. It doesn't describe output format or edge cases, but the key behavioral traits are covered.

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 description is compact and front-loaded, starting with the payment notice and operation list. Every sentence adds functional information, and the structure maps cleanly to the schema's op property. No filler or redundancy.

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?

Given the tool has 11 parameters and no output schema, the description covers all operations, parameter roles, and the payment challenge. It lacks explicit mention of return shape, but for a multi-mode calculation tool the core usage context is sufficiently complete.

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 100%, so baseline is 3. The description adds semantic value by grouping parameters per operation (duration/date for add/subtract, from/to/units for diff, days/weekend/holidays for business-add/diff). This explains how parameters interplay beyond individual schema descriptions.

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 clearly states the tool performs calendar date math with four explicit operation modes: add/subtract durations, diff datetimes, and business-day add/diff. It distinguishes itself from sibling tools like timezone and cron by specifically enumerating date-math operations and the ISO-8601 duration format.

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 gives concrete usage patterns per operation (e.g., 'op='add'/'subtract' an ISO-8601 duration...'), and mentions the payment requirement and challenge flow. It does not explicitly compare to sibling tools or state when not to use it, but the self-contained usage guidance is clear.

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