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

No annotations are provided, so the description carries the full burden, yet it discloses nothing about behavior: whether it is a pure computation, what it returns, or how it treats the four inputs (a, b, start, end). There is no information at all beyond the name.

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?

It is very short, but this is under-specification rather than conciseness: the single repeated fragment carries no information, so there is nothing front-loaded or earned.

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?

Four ambiguous optional parameters, no annotations, no output schema, and a tautological description leave an agent with no basis for constructing a correct call. The definition is effectively incomplete for this tool's complexity.

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?

Coverage is nominally 100%, but the schema descriptions are content-free placeholders ('A to process', 'Start to process'), so the schema adds no real semantics either. The description does nothing to disambiguate why a tool named 'date diff' needs all of a, b, start, and end, or which are required (none are).

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 is 'Date Diff: Date Diff', which merely restates the tool name twice. It hints at the domain (date difference) but states no verb, no required inputs, and nothing that distinguishes it from siblings like x402-days-between, x402-date-math, or x402-difference.

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?

No when-to-use guidance, no prerequisites, and no mention of any alternative. With numerous overlapping date/difference siblings (x402-days-between, x402-difference, x402-date-math), the absence of routing guidance leaves an agent unable to choose correctly.

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