mortgage_piti_calculatorMortgage PITI Calculator — Calculate your full monthly PITI mortgage payment—principal, interest, property taxes, homeowners insurance, and PMI. Full amortization schedule included.
| Name | Required | Description | Default |
|---|---|---|---|
| homeValue | Yes | ||
| termYears | Yes | ||
| loanAmount | Yes | ||
| pmiRatePct | Yes | ||
| annualRatePct | Yes | ||
| annualInsuranceDollars | Yes | ||
| annualPropertyTaxRatePct | Yes |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses the main output (monthly PITI payment plus a full amortization schedule) and the included components. It does not describe detailed behavior such as how PMI or property tax rates are applied, rounding, or the exact structure of the schedule.
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?
Two sentences: the first names the result and components, the second notes the amortization schedule. No filler, and it is front-loaded with 'Calculate your full monthly PITI mortgage payment'.
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?
The description is adequate for a straightforward calculator: it states the expected output (monthly payment and schedule) and the component categories. However, with 7 required parameters, no output schema, and no annotations, it does not fully clarify the return format or calculation assumptions, leaving some gaps.
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 has 0% description coverage, so the description must compensate. It groups the seven parameters into the PITI terms (principal, interest, property taxes, homeowners insurance, PMI) and the schedule, adding context beyond bare names. However, it does not explain the input relationships or formulas (e.g., tax rate applied to homeValue, how pmiRatePct is used).
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 uses a specific verb 'Calculate' tied to the resource 'full monthly PITI mortgage payment', enumerating components (principal, interest, property taxes, homeowners insurance, and PMI) and notes the full amortization schedule. This clearly distinguishes it from sibling mortgage calculators such as loan_amortization_calculator or mortgage_points_calculator.
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?
The description implies usage when a complete PITI payment including taxes, insurance, and PMI is needed, and mentions the amortization schedule. However, it offers no explicit guidance on when to prefer this tool over sibling calculators (e.g., mortgage_overpayment_calculator, mortgage_refinance_calculator) and no exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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