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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only names the computation ('future value of an annuity') without stating assumptions such as ordinary versus annuity-due timing, compounding conventions, return format, or side effects. This is minimal and not contradictory.

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 description is a single front-loaded sentence with no filler or redundant elaboration. It is efficient, though the 'Annuity Fv:' prefix is nearly redundant with the tool name.

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?

Even though the tool has no parameters, it has no output schema, and the description does not explain the return value, formula conventions, or why a future-value calculator accepts no inputs. Against a sibling list of thousands of tools, this is not enough context for an agent to use it correctly.

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?

The input schema has zero parameters and schema description coverage is 100%, so there are no parameter semantics for the description to clarify. The baseline for a zero-parameter tool applies.

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 identifies the domain ('annuity') and the calculation ('future value'), so the general purpose is recognizable. However, it is a noun phrase rather than an explicit action such as 'calculates the future value,' and it does not distinguish this tool from related siblings like x402-future-value or x402-annuity-pv.

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 guidance about when to use this tool versus alternatives. The description does not mention x402-annuity-pv, x402-future-value, or any condition that would select this tool, so the agent is left to infer usage from the name and the sibling list.

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