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

Beyond the annotations it discloses month-end clamping semantics (31 Jan + 1 month = 28/29 Feb), weekend skipping for business days, the negative-number convention for subtraction, and a concrete cost of $0.001 USDC on Base per successful call paid via x402. The payment side effect is exactly the kind of behavioral context annotations cannot convey.

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 core action is front-loaded, and each following sentence carries distinct necessary information (subtraction convention, business-day behavior, clamping rule, typical use, price). No filler or repetition.

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 carry-over annotations, the description supplies the semantics an agent needs (clamping, weekend skipping, cost). It does not state the return shape or timezone handling, a minor gap for a date-arithmetic tool.

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 the four parameters are already documented, and the description reinforces the semantics of negatives and weekend skipping. However, it advertises years, weeks, hours and minutes, which do not exist in the schema — an agent could attempt invalid arguments, and that mismatch offsets the added meaning.

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 states a precise verb+resource (add/subtract offsets to a date) and enumerates the supported units plus the business-day mode, which is immediately distinguishable from the sibling date_diff. An agent can tell what this does without opening the schema.

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?

"Use to compute due dates and expiries" gives clear intended context, and the negative-number note tells the agent how to handle subtraction in the same call. It stops short of naming a when-not case or pointing at alternatives like date_diff, so it is clear but not exhaustive.

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