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

No annotations are provided, so the description carries the full burden. It discloses rounding to two decimals and a payment/trial condition, but says nothing about compounding frequency (annual vs. periodic), handling of negative rates, or precision/error behavior. The unexplained coexistence of 'n'/'years' and 'pv'/'present' parameters is a behavioral gap the description never resolves.

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 computational statement is front-loaded and efficient, but the trailing '🆓 5 free trial calls per signed wallet' promo is marketing noise that occupies description space without helping the agent invoke the tool.

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 5-parameter tool with zero schema descriptions, no annotations and no output schema, the description does not provide enough to call it correctly: required parameters are unknown and the overlapping parameter names are left unresolved.

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% across 5 string parameters. The description loosely maps to 'present', 'rate' and 'years' but never explains 'n' or 'pv', nor whether 'n' is a period count distinct from 'years' or whether 'pv'/'present' are aliases. That ambiguity is exactly the information the description needed to supply.

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 ('Computes compound future value') plus the inputs used (present, annual rate percent, years) and the rounding behavior. It is clear on its own, but it does not distinguish itself from close siblings such as x402-compound-interest, x402-compound, or x402-present-value.

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 when-to-use guidance and no alternative named. With siblings like x402-compound-interest, x402-compound, x402-annuity-fv and x402-simple-interest in the catalog, the agent is left to guess which tool fits a given finance question.

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