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. It only names the operation and says nothing about input format, output shape, side effects, determinism, or edge cases. An agent cannot infer any behavioral contract beyond the tool's name.

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 extremely short, but the second phrase merely repeats the first; it is under-specification rather than purposeful conciseness. Not every word earns its place because the content adds no information beyond the tool name.

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 a description that only restates the name, the tool is not adequately specified. An agent cannot determine what input is expected (e.g., an array), what the return value looks like, or what distinguishes this from cumulative-sum and running-total.

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 has zero properties, so schema description coverage is effectively 100% and there are no parameter meanings to explain. The baseline of 4 applies because the description is not required to compensate for missing parameter documentation.

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 'Cumulative sum array' is an exact restatement of the tool name 'x402-cum-sum-array' — a noun phrase with no verb or distinct resource. It does not differentiate the tool from closely related siblings such as x402-cumulative-sum, x402-running-total, or x402-cum-product-array.

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 on when to use this tool versus any alternative. The description does not mention related tools like cumulative-sum or running-total, nor does it provide any context about input requirements or expected use cases.

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