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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it discloses nothing. It does not mention whether inputs are ISO timestamps, Date objects, or epoch values, what unit the result uses (hours? decimal? rounded?), or any edge-case behavior. Even the parameter names 'a'/'b' vs 'start'/'end' suggest two possible invocation styles, but no guidance resolves this ambiguity.

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 small, but this is under-specification, not conciseness. 'Hours Between: Hours Between' is a direct repetition of the tool name with no informational content, so its brevity earns no credit. A single descriptive sentence stating what the tool computes and with what inputs would have been equally concise and useful.

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 tool with 4 parameters, no annotations, and no output schema, this description is wholly inadequate. The agent lacks: input format specification, which parameters to supply, whether parameters are optional (0 required), what the returned value represents, and how this relates to sibling date/time tools. Every dimension an agent needs to invoke it correctly is missing.

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?

Although schema coverage is reported as 100%, every parameter description is semantically empty filler ('A to process', 'End to process'). The description adds no meaning on top of the schema, so an agent cannot tell whether 'a' and 'b' are start/end aliases, whether 'start'/'end' are the canonical pair, or what string format each parameter requires. The value is zero for all four parameters.

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 'Hours Between: Hours Between' is a pure tautology that merely repeats the tool name with zero added information. It states no verb, no resource, no input semantics, and no output. An agent cannot determine what this tool computes, what input format is expected, or how it differs from siblings like x402-add-hours, x402-date-diff, or x402-elapsed-time.

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 zero guidance on when to use this tool vs. the many related siblings (x402-days-between, x402-weekdays-between, x402-date-diff, x402-duration). No context, no exclusions, no alternative routes are mentioned. The completely generic parameter descriptions ('A to process', 'B to process') further fail to indicate what situations call for this tool.

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