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 the result is a pure computation, what units are expected or returned, nor what the output looks like. The single tautological sentence adds zero behavioral context.

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 short but not concise in a useful sense — it is under-specified rather than economical. Its single clause repeats the tool name without contributing information an agent could act on.

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?

A physical-quantity calculator with no annotations, no output schema, and no description of units, formula (½mv²), or return value. An agent cannot determine input units (kg vs g, m/s vs km/h) or expected output, so the definition is inadequate 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% (both 'mass' and 'velocity' are documented), so the baseline is 3 per the rubric. The description adds no unit or format meaning beyond the schema, and the schema's own text ('Mass to process', 'Velocity to process') is thin, but the coverage threshold sets the floor here.

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 "Kinetic Energy: Energy of kinetic" merely restates the tool name in a tautological phrase, offering no verb, computational definition, or formula. It does not distinguish this tool from near-identical siblings such as x402-potential-energy, x402-work, or x402-momentum.

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 on when to use this tool versus alternatives. With dozens of physics siblings (potential-energy, work, momentum, force, impulse) in the catalog, the absence of any routing hint leaves selection entirely to guesswork.

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