Compute compound future or present value and periodic loan payments from principal, annual rate, and years. Use it to solve finance problems with adjustable compounding periods.
Calculate compound future/present value or periodic loan payment.
| Name | Required | Description | Default |
|---|---|---|---|
| years | Yes | ||
| operation | Yes | ||
| principal | Yes | ||
| periodsPerYear | No | ||
| annualRatePercent | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does 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 state that this is a pure, side-effect-free calculation, nor what conventions it assumes (nominal vs effective rate, end-of-period payments, rounding). For a numerics tool these assumptions materially change results and none are disclosed.
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?
One short, front-loaded sentence with no wasted words. It is arguably too terse for a five-parameter financial tool, but nothing in it is filler.
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?
With 0% schema description coverage, no annotations, and no output schema, the description would need to explain rate units, compounding periods, and payment timing to be callable correctly. It supplies none of that, leaving significant ambiguity for a required-parameter tool.
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 five parameters, and the description names none of them. It never clarifies that annualRatePercent is in percent (not decimal 0.05), that periodsPerYear defaults to 12, or that the operation selects which of the three formulas runs — all of which an agent must infer.
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?
Specific verb (Calculate) plus the three distinct results it can produce (compound future value, present value, periodic loan payment), which map cleanly onto the operation enum. It is distinguishable from siblings like calculate_percentage or calculate_matrix, though it never explicitly contrasts itself with them.
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?
No statement of when to use this tool versus calculate_expression, calculate_percentage, or any other sibling. The only implied guidance is the operation names themselves inside the schema enum, which the description merely echoes.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.