FreeDailyPro Calculators

calculate_loan

Read-onlyIdempotent

Loan calculator — EMI / amortizing loan, with an optional first payment date that dates the schedule preview and gives the payoff date

Input Schema

Name	Required	Description
`years`	Yes
`principal`	Yes
`previewMonths`	No
`firstPaymentDate`	No	Optional date the first payment is due, as YYYY-MM-DD. Adds a date to every schedulePreview row and returns firstPaymentDate, lastPaymentDate and payoffDate for the whole loan. It only labels the schedule; the amounts do not change. A payment day of 29 to 31 moves to the last day of shorter months.
`annualRatePercent`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 28, 2026

addedInput schema / properties / firstPaymentDate

Added value: +{
+  "description": "Optional date the first payment is due, as YYYY-MM-DD. Adds a date to every schedulePreview row and returns firstPaymentDate, lastPaymentDate and payoffDate for the whole loan. It only labels the schedule; the amounts do not change. A payment day of 29 to 31 moves to the last day of shorter months.",
+  "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+  "type": "string"
+}

First observedOct 24, 2026

TDQS

B3/5.0

Behavior3/5

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

Annotations already establish that this is a read-only, idempotent, non-destructive calculation. The description adds that firstPaymentDate only labels the schedule and does not change amounts, and that short-month date handling applies, but it does not describe the full output shape or previewMonths behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The definition is a single, front-loaded sentence that identifies the calculation type before explaining the optional date behavior. It is efficient, though the dash construction packs multiple ideas into one long clause.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a five-parameter calculator with no output schema, the description is adequate but incomplete. It covers the special date parameter, but leaves previewMonths and the main calculation parameters unexplained and does not fully describe the return values.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is only 20%, with only firstPaymentDate documented. The description repeats that date's role but adds no meaning for principal, annualRatePercent, years, or previewMonths, so it fails to compensate for the low schema coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific resource and calculation type: "Loan calculator — EMI / amortizing loan." This distinguishes it from generic interest calculators, though it does not explicitly differentiate from the sibling converters_amortization tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives no guidance on when to choose this tool versus alternatives such as converters_amortization, calculate_simple_interest, or converters_student_loan. The optional firstPaymentDate behavior is explained, but that is parameter behavior rather than tool-selection guidance.

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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