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 reveals nothing about input format, return value, side effects, or whether the operation is read-only. 'Complex Sub' gives an agent no behavioral insight beyond the name itself.

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 consists of two tokens that merely restate the name. This is under-specification, not conciseness, since the field contributes no information and does not earn its place. The 'Process' calibration example demonstrates that tautological stubs score low on this dimension.

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?

The tool likely requires complex numbers to subtract, but the schema has no parameters and the description does not state how input is provided or what the output looks like. With no output schema and no annotations, the description leaves every practically relevant detail unspecified.

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 is empty, so there are no parameters for the description to clarify. Per the rubric, 0 parameters warrants a baseline of 4. However, the empty schema is surprising for a subtraction tool and the description does not explain how operands are supplied, which slightly undermines usability.

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 a verbatim repetition of the tool name: 'Complex Sub: Complex Sub'. It states no action, resource, or scope, and does not even explicitly say it performs complex-number subtraction, though sibling tools like x402-complex-add and x402-complex-mul hint at it. This is a tautology, not a purpose statement.

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 related siblings such as x402-complex-add, x402-complex-mul, or x402-complex-div. No context, alternatives, or exclusions are provided, leaving an agent with zero basis for selecting this tool.

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