amortization

mcp-amortization

In the official MCP Registry (io.github.theluckystrike/amortization). Loan and lease schedules for an AI assistant. Give it the terms of a credit agreement, the amount, the nominal annual rate in basis points, how often interest compounds, how often a payment falls due, the term in periods, the method, any arrangement fee and any balloon, and it works out the payment, the effective annual rate, and the schedule period by period: opening balance, payment, interest, principal, closing balance. It answers what settling early would cost and save, and hands back the double entry for a payment in the same account names the cash book uses. Everything is integer minor units, and every closing balance reaches the balloon, or zero, exactly. Nothing is sent anywhere: the register is a file on your machine.

npm publish for @theluckystrike/mcp-amortization is pending, so npx -y @theluckystrike/mcp-amortization returns 404 today. Until then, the .mcpb one-click bundle or a clone+build is the working path.

Install

Claude Desktop, macOS ~/Library/Application Support/Claude/claude_desktop_config.json, Windows %APPDATA%\Claude\claude_desktop_config.json:

{
  "mcpServers": {
    "amortization": {
      "command": "npx",
      "args": ["-y", "@theluckystrike/mcp-amortization"]
    }
  }
}

claude mcp add amortization -- npx -y @theluckystrike/mcp-amortization

Cursor, ~/.cursor/mcp.json (global) or .cursor/mcp.json (project). Same entry as Claude Desktop.

Tools

Tool	What it does
loan_create	Record a loan or lease from its terms. Returns LOAN-YYYY-NNNN, the level payment, the effective annual rate and the total interest
loan_schedule	The schedule: opening, payment, interest, principal, closing for every period, and the total interest
loan_repay_early	What settling or overpaying at a period costs: the outstanding balance, the penalty, the recalculated remaining schedule and the interest saved, gross and net of the penalty
loan_journal	The double entry for a period or a month: debit interest expense and loan liability, credit cash, plus an expense_add-ready payload
loan_list	The register, with the balance outstanding and the next payment date at any date
loan_delete	Remove one agreement and give its slot back. Refused, with the entry named, if a journal has already been taken from it
loans_report	What is owed per currency, when each next payment falls due, and the interest charged in a calendar year
license_status, license_activate	Your tier, and activating a Pro key

Free vs Pro

	Free	Pro
Loans in the register	3	Unlimited
Schedules	Unlimited	Unlimited
Delete an agreement (loan_delete)	Yes	Yes
Early repayment (loan_repay_early)	-	Yes
Journals (loan_journal)	-	Yes
Report (loans_report)	-	Yes

loan_delete is free on purpose. The cap is on agreements held, so recording the same lease twice would otherwise cost two of the three slots with no way back but a key; a duplicate is refused by loan_create before anything is written, naming the record it matches, and anything already in the register comes back out with loan_delete. A loan a journal has been taken from is refused instead, and named, because those lines are already in somebody's ledger.

The schedule is never metered. The payment and the interest are the question this server exists to answer, and a free tier that hides the answer is a demo. The meter is on the number of agreements held, which is the unit of work.

Get Pro: https://mcp.zovo.one/buy/amortization, $19 one-time for this server, or $39 for the bundle.

A measured insight

Quoting a rate per quarter as the nominal rate over four is worth 1.0 percent of the interest, in the lender's favour. Take EUR 10,000 at a nominal 12 percent compounded MONTHLY, repaid in four quarterly instalments. The rate for one quarter is the equivalent rate, (1 + 0.12/12)^3 - 1 = 3.0301 percent, not 0.12/4 = 3.0000 percent. That 3-basis-point difference sets the payment at EUR 2,692.21 instead of EUR 2,690.27 and the total interest at EUR 768.84 instead of EUR 761.08: EUR 7.76 more, 1.0 percent of the whole interest bill, on a one-year loan of ten thousand. The two rates look identical in a quote and diverge in the schedule, which is why this server takes every equivalent rate through the compounding clock and prints the periodic rate it used to six decimal places.

The same arithmetic is why the effective annual rate is reported beside the nominal one on every loan: a nominal 12 percent compounded monthly is an effective 12.68 percent, and 0.68 of a percent is the part of the price the headline rate does not carry.

Privacy

All data stays local, in ${XDG_DATA_HOME:-~/.local/share}/mcp-servers/amortization/. Two files: loans.json and counter.json. No network call is made by this server at all, for any tool. No schedule is stored: every row is derived from the terms on the call, because a stored schedule is a second copy of a figure the rate and the term already decide, and the copy is the one that gets believed after somebody edits the rate.

Built by theluckystrike. https://github.com/theluckystrike

Use these docs as an MCP server

Any MCP client (Claude, Cursor, Windsurf, VS Code) can read this repository's documentation directly via GitMCP - no install:

• Docs MCP URL: https://gitmcp.io/theluckystrike/mcp-amortization