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

No annotations are provided, so the description carries the full disclosure burden, and it discloses nothing: not whether input is a numeric string, not rounding/precision behavior, not output format. For a trivial pure conversion this burden is light, but the description still adds zero behavioral context beyond the title.

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 short, front-loaded sentence with no padding or repetition. It is appropriately sized for a simple tool, though it is arguably too terse to be maximally 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?

With no annotations, no output schema, zero required parameters, and an ambiguous two-parameter schema, the description should at least state the expected input form and which field to use. It leaves an agent guessing on a tool that otherwise looks trivial.

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 100%, so the baseline is 3. The schema itself is confusing (two optional params, 'km' and 'value', both vaguely described as 'to process'), and the description does nothing to clarify which parameter should carry the input, so it neither compensates nor fully satisfies.

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 specific verb and conversion direction ('Convert km to miles'), which is unambiguous on its own. However, it does nothing to distinguish itself from the directly inverse sibling x402-miles-to-km or from the many other unit-conversion siblings, so the agent must rely on the tool name alone for disambiguation.

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, no mention of the inverse tool x402-miles-to-km, and no note about input expectations. The description simply restates the operation with no routing or context cues.

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