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

No annotations exist, so the description bears the full disclosure burden. It usefully states the payment model ("5 free trial calls per signed wallet"), but says nothing about unit handling, validation of the string-typed numeric inputs, error behavior, or what the response contains.

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?

Two short clauses, formula front and center, no padding. The emoji and trial-call note are minor but do not obscure the core statement.

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 simple two-parameter physics tool with no output schema and no annotations, the description should at minimum pin down units and result units. It leaves both undefined, so an agent cannot confidently call it 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 the description only supplies the abstract formula W=Fd. It never states the expected units (newtons vs. pounds, meters vs. feet) or that the two string parameters must be parseable numbers, so an agent could easily supply mismatched units or non-numeric strings.

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?

"Work calculation (W=Fd)" names a specific quantity and gives the formula, which is enough to separate it from siblings like x402-energy, x402-power, or x402-force. It does not explicitly contrast with those siblings, so it stops short of a 5.

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 formula implies what inputs produce what, but there is no explicit when-to-use guidance, no mention of when to prefer x402-force / x402-kinetic-energy / x402-potential-energy instead, and no prerequisites beyond the pricing note.

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