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

No annotations are provided, so the description carries the full behavioral burden, and it discloses very little: it implies a pure computation but says nothing about output shape, rounding rules, error behavior on unparseable dates, or timezone assumptions. The one piece of real behavioral information is the '5 free trial calls per signed wallet' note, which signals a paid/auth dimension but not how it behaves.

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 front-loaded sentence that states the operation and its outputs, followed by a short promo clause. Efficient and well ordered, with no wasted prose, though the promo line is not functional content.

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 0% parameter coverage, the description needs to carry a lot and does not. It never explains the a/b vs start/end parameter pairing, input date format, or the exact return structure, all of which an agent needs before calling it.

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% with four undocumented parameters (a, b, end, start) and no enums. The description says the tool works on 'two date-times', which does convey that the inputs are dates, but it never resolves the obvious ambiguity of whether a/b are aliases for start/end or what string format is expected, leaving half the parameters unexplained.

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 and resource ('Computes the difference between two date-times') and names the output units (rounded hours, minutes, days), so the operation is unambiguous. It does not differentiate from close siblings such as x402-days-between, x402-date-diff, or x402-elapsed-time, which is the only thing keeping it from a 5.

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 when-to-use guidance at all: no statement of when this is preferable to x402-days-between, x402-date-diff, or x402-elapsed-time, and no mention of prerequisites such as input format or timezone handling. The only context offered is a pricing/promo note, which is not usage guidance.

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