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

With no annotations, the description carries the full load. It does disclose that this is a deterministic multiplication (behaviourally safe and side-effect free) and adds metering context ('5 free trial calls per signed wallet'), which is genuinely useful. It does not say what the response looks like or whether units are echoed back.

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 definition is front-loaded: operation, formula, then inputs, with the pricing note at the end. The emoji-laden trial line is marketing rather than tool guidance, a minor bit of waste, but nothing obscures the core instruction.

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 two-input arithmetic tool with no output schema, the description is close to sufficient — the formula implies the return value. Missing unit conventions and output format keep it from being complete, but the omission is modest given the tool's simplicity.

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 coverage is 0% and both parameters are untyped strings with no description. The description names 'force' and 'time' but never specifies units (newtons, seconds?), format, or whether values are numeric strings — a serious gap for a physics calculation where unit mismatches silently produce wrong answers.

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?

States a specific verb and resource ('Calculate impulse') and even supplies the formula (force multiplied by time), so the operation is unambiguous. It does not contrast itself against near-neighbours like x402-force, x402-work, or x402-momentum, but the purpose itself is clear.

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?

'Provide force and time values' hints at the call shape but gives no when-to-use guidance, no distinction from the many adjacent physics calculators in the sibling list, and no prerequisites. The agent must infer selection purely from the tool name.

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