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

With no annotations, the description carries the full behavioral burden, and it discloses almost nothing about the operation itself — no indication of whether this is a pure computation, what it returns, or how invalid units are handled. The one genuinely useful disclosure is the payment/rate-limit detail (5 free trial calls per signed wallet), which tells the agent about cost but not about behavior.

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 text is short and front-loaded, but that brevity reflects under-specification rather than economy: the first sentence is a tautology and the second is a promotional billing note. Nothing in it helps an agent call the tool correctly.

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 3-parameter tool with zero schema coverage, no annotations, and no output schema needs the description to explain the conversion contract, accepted unit identifiers, and return shape. The description covers none of this, leaving the definition unusable without guessing.

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 0% and all three parameters (to, from, value) are undocumented. The description supplies no meaning for them — it does not state that value is the amount and to/from are source and target units, nor what unit strings are accepted.

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?

"Power Unit: Power of unit" restates the tool name rather than stating a verb and resource. An agent cannot tell whether this converts power units (watts/horsepower), computes a power quantity, or performs an exponentiation-like operation — and cannot distinguish it from siblings such as x402-power, x402-electric-power, or x402-force-unit.

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?

The description gives no when-to-use context, no exclusions, and no routing to any of the many adjacent tools (x402-power, x402-power-v-i, x402-power-series, x402-electric-power). The only actionable sentence concerns free trial calls, which is billing information, not usage guidance.

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