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 nothing: not whether inputs accept numeric strings, whether zero 'whole' is handled, nor what the output looks like. There is no behavioral content whatsoever.

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 extremely short, but the brevity is under-specification rather than concision — repeated words carry no information. Nothing is front-loaded because there is nothing to front-load.

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 two ambiguous string parameters, the description should explain the computation and input format. It is completely inadequate for even a trivially simple tool.

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%, which sets the baseline at 3 even though the description adds no parameter meaning. The schema's own text ('Part to process', 'Whole to process') is thin and leaves the part/whole arithmetic relationship to inference, but the description neither improves nor degrades on it.

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 'Percentage Of: Percentage Of', a tautology that merely restates the tool name. It never states the operation (dividing 'part' by 'whole' and converting to a percent) or the return form, so an agent cannot tell it apart from siblings like x402-percent-of, x402-percent-of-value, or x402-percentage-change.

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 prerequisites, and no mention of any alternative. With dozens of near-identical percent tools among the siblings, the absence of routing guidance is particularly costly.

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