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

No annotations are provided, so the description carries the full burden of behavioral disclosure, and it reveals nothing. It does not state what computation is performed, what inputs are consumed, what output is produced, or whether any side effects exist. For a calculation tool this is a complete transparency failure.

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 only four words long, but this is under-specification rather than conciseness. There is no informative content to structure, and the space used is entirely wasted on repeating the tool name instead of conveying meaning.

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, an empty input schema, and a sibling list containing many near-identical percent-related tools, the description is catastrophically inadequate. It does not enable an agent to select, invoke, or interpret this tool correctly under any circumstances.

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 schema has zero parameters, so there is nothing for the description to document; however, a tool named 'percent-of' inherently requires numeric inputs, and the empty schema combined with a tautological description leaves the agent unable to determine how inputs are supplied. The description should have clarified the input mechanism (e.g., natural-language query), but it adds nothing.

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 'Percent Of: Percent Of' is a pure tautology that merely restates the tool name. It fails to specify whether the tool computes what percentage one number is of another, applies a percentage to a value, or something else, and it does nothing to distinguish itself from dozens of near-identical siblings like x402-percentage-of, x402-percent-of-value, x402-proportion-of, and x402-ratio-of.

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 versus its heavily overlapping siblings (x402-percentage-of, x402-percent-change-of, x402-percent-of-value, x402-fraction-to-percent, and many more). An agent has no way to decide which 'percent' tool to invoke, making the selection effectively random.

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