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. It discloses no behavior: no read/write safety, no input mechanism despite claiming 'two moments', no output unit or format, and no side effects. This is only a definition, not a behavioral contract.

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 text is short, but 'Elapsed Time:' duplicates the tool name and the remainder is an under-specified noun phrase. This is under-specification rather than genuine conciseness, and it lacks any structured information about inputs, usage, or output.

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 and no output schema, the description is severely incomplete for a time utility. It doesn't state the output unit, how the two moments are supplied, what happens when moments are invalid or absent, or how it differs from the many sibling time tools. An agent cannot reliably invoke it correctly.

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?

The input schema is empty, so there are no parameters to document; however, the phrase 'between two moments' implies inputs the schema doesn't expose. The description gives no format, names, or mechanism for those moments, so the apparent parameter semantics are ambiguous.

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 effectively a tautology: 'Elapsed Time: Elapsed time between two moments' restates the tool name and uses a noun phrase rather than a verb like 'calculates'. It doesn't specify what input it consumes or how it differs from sibling time/duration tools such as x402-duration and x402-date-diff.

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, exclusions, or alternative tools are mentioned. With hundreds of time/date siblings, an agent has no basis for choosing this over x402-time-until, x402-relative-time, or x402-days-between. It isn't misleading, but the guidance is absent.

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