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 does not disclose the annuity convention (ordinary vs annuity due), whether rate is per-period or annual, sign conventions for payment, rounding, or error behavior. For a financial calculation invoked without annotations, this is a meaningful gap.

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 single sentence is short and front-loaded with the operation name and meaning. There is no waste, though it is arguably too terse to be a complete definition.

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?

Tool has 3 parameters, no output schema, and no annotations. The description omits the calculation assumptions and input conventions that an agent needs to call a finance function correctly, leaving the definition materially incomplete.

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%, so the baseline is 3, but the schema text ('Rate to process', 'Payment to process', 'Periods to process') is tautological and the description adds nothing beyond it. It does not clarify units, periodicity, or string-format expectations for rate/payment/periods.

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 names a specific resource and operation: future value of an annuity. An agent can tell it is a finance calculation, but it never distinguishes itself from the sibling x402-annuity-pv (present value) or x402-future-value, so the boundary is only inferable from the name.

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, no prerequisites, and no mention of the obvious alternative x402-annuity-pv or x402-future-value. The agent is left to infer usage entirely 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.