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 discloses nothing. It does not state the output shape, whether the input is a comma-separated list or JSON array, or how the first element is handled.

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 short, but shortness here reflects under-specification rather than efficiency: the same phrase is duplicated and neither instance carries 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?

For a computational tool with no annotations and no output schema, an agent needs to know the input format and the meaning of the returned series. The description supplies none of this, leaving the definition unusable for correct invocation.

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 by rule; the single 'values' parameter is documented in the schema, though only as the vacuous 'Values to process'. The description adds no format or delimiter information beyond the schema.

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 Change Array: Percent Change Array' is a pure tautology that merely restates the tool name twice. It gives no verb, no explanation of what is computed, and does nothing to distinguish this tool from near-identical siblings such as x402-percentage-change, x402-percent-change-of, or x402-rate-of-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 guidance whatsoever about when to use this tool, what input shape it expects, or which alternative percent-change tool to pick instead. With roughly a dozen percent-change variants in the sibling list, this omission is disqualifying.

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