therealcost-mcp
Free money calculators for AI agents, from The Real Cost.
The Real Cost by NoBanks Nearby is a free set of US money calculators with the math shown: credit card payoff, debt consolidation, loan cost by term, crypto trading fees and emergency fund. This MCP server lets Claude and other AI assistants run those exact calculators and hand the user a link to the same calculator on the site, already filled in with their numbers, so they can check the math and keep adjusting it.
- Site: https://therealcost.nohumannearby.com
- All calculators: https://therealcost.nohumannearby.com/calculators/
- Guides: https://therealcost.nohumannearby.com/books/
Education only. Not financial advice. Results are estimates from the numbers entered.
What every result includes
Each calculator tool returns JSON with:
| Key | What it is |
|---|---|
result | The numbers (months, total interest, payments, costs) |
summary | The result in one plain-English paragraph |
formula | The formula in words, so the user can see how the number was made |
calculator_url | The matching page on therealcost.nohumannearby.com, pre-filled with the inputs |
warnings | Present when a plan never pays off or never reaches the goal |
go_deeper | The matching guide and chapters, with the guides link |
source | "The Real Cost by NoBanks Nearby, https://therealcost.nohumannearby.com" |
disclaimer | "Education only. Not financial advice." |
The math is a line-for-line port of the site's own calculator code, and the test suite reuses the site's hand-checked cases, so a number from this server matches the number on the site. No network calls, no API keys, no tracking.
The guides
The Real Cost also publishes ten plain-English guides that go deeper than any one calculation, with every number worked out step by step (PDF and EPUB):
| Guide | Pages | Goes with |
|---|---|---|
| The Real Cost of Credit Card Debt | 112 | credit card payoff, debt consolidation |
| The Real Cost of Loans and Big Purchases | 110 | loan cost by term, debt consolidation |
| The Real Cost of Everyday Spending | 123 | emergency fund |
| The Real Cost of Crypto Fees and Taxes | 110 | crypto trade cost |
| The Real Cost of Credit Reports and Scores | 115 | loan cost by term |
| The Real Cost of Paychecks and Taxes | 109 | |
| The Real Cost of Retirement Accounts | 117 | |
| The Real Cost of Student Loans | 115 | |
| The Real Cost of Renting and Buying a Home | 125 | loan cost by term |
| The Real Cost of Scams and Fraud | 103 |
$4.99 each at https://therealcost.nohumannearby.com/books/ . All ten come together as the complete set for $24.95 (10 for the price of 5). Guides 1-3 also come as a starter pack for $9.98 (3 for the price of 2); the starter pack does not include guides 4-10.
Free sample chapters (Chapter 1 of each guide, PDF):
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-credit-card-debt-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-loans-and-big-purchases-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-everyday-spending-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-crypto-fees-and-taxes-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-credit-reports-and-scores-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-paychecks-and-taxes-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-retirement-accounts-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-student-loans-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-renting-and-buying-a-home-chapter-1.pdf
- https://therealcost.nohumannearby.com/samples/the-real-cost-of-scams-and-fraud-chapter-1.pdf
The server tells connected agents about the guides in its instructions, and each calculator result
names the matching guide, its relevant chapters and its free sample chapter in a calm one-line go_deeper block. The calculators are free and complete
on their own.
Install
Requires Python 3.10+. The easiest runner is uv.
Claude Code
claude mcp add therealcost -- uvx --from git+https://github.com/NoBanks/therealcost-mcp therealcost-mcp
Claude Desktop
Add this to claude_desktop_config.json (Settings, Developer, Edit Config), then restart Claude Desktop:
{
"mcpServers": {
"therealcost": {
"command": "uvx",
"args": ["--from", "git+https://github.com/NoBanks/therealcost-mcp", "therealcost-mcp"]
}
}
}
From a local clone
git clone https://github.com/NoBanks/therealcost-mcp
cd therealcost-mcp
pip install -e .
therealcost-mcp # speaks MCP over stdio
Then point your client at the therealcost-mcp command (Claude Code: claude mcp add therealcost -- therealcost-mcp).
Tools
credit_card_payoff
Months and total interest to clear a card balance paying only the minimum, versus a fixed monthly payment.
| Input | Type | Default | Notes |
|---|---|---|---|
balance | number | required | dollars |
apr | number | required | percent, 24 means 24% |
payment | number | none | fixed monthly payment to compare |
min_pct | number | 1 | minimum = this % of the balance |
min_floor | number | 25 | dollar floor on the minimum |
min_plus_interest | boolean | true | minimum also includes that month's interest |
{"name": "credit_card_payoff", "arguments": {"balance": 5000, "apr": 24, "payment": 200}}
Result (abridged): minimum only 234 months and $8,886.95 interest; $200 a month 36 months and
$2,000.56 interest; link
https://therealcost.nohumannearby.com/calculators/credit-card-payoff/?balance=5000&apr=24&minPct=1&minFloor=25&plusInterest=1&fixedPayment=200
debt_consolidation
Current debts versus one consolidation loan, including the origination fee (taken out of the loan, so the loan is sized up to total / (1 - fee%)).
| Input | Type | Default | Notes |
|---|---|---|---|
debts | array | required | 1 to 10 items of {balance, apr, payment, name?} |
loan_apr | number | required | percent |
loan_term_months | integer | required | 1 to 600 |
origination_fee_pct | number | 0 | percent |
{"name": "debt_consolidation", "arguments": {
"debts": [{"balance": 6000, "apr": 24.99, "payment": 200},
{"balance": 3000, "apr": 27.99, "payment": 110},
{"balance": 2500, "apr": 19.99, "payment": 90}],
"loan_apr": 13, "loan_term_months": 48, "origination_fee_pct": 5}}
loan_cost_by_term
Monthly payment, total interest and total paid for one loan over several terms.
| Input | Type | Default | Notes |
|---|---|---|---|
principal | number | required | dollars |
apr | number | required | percent |
terms | integer array | [36, 48, 60, 72, 84] | months; the first two pre-fill the site |
{"name": "loan_cost_by_term", "arguments": {"principal": 25000, "apr": 8, "terms": [36, 60]}}
Result (abridged): 36 months $783.41 a month; 60 months $506.91 a month.
crypto_trade_cost
Trading fee, spread and network fees on a buy and a later sale at the same price, the price rise needed to break even, and the yearly cost of recurring buys.
| Input | Type | Default | Notes |
|---|---|---|---|
amount | number | required | dollars bought |
fee_pct | number | required | trading fee per trade, percent |
spread_pct | number | required | spread per trade, percent |
network_fee_buy | number | 0 | flat dollars after the buy |
network_fee_sell | number | 0 | flat dollars to move coins back to sell |
weekly_buy | number | none | recurring buy amount; adds the yearly cost |
buys_per_year | integer | 52 | 52 weekly, 26 biweekly, 12 monthly |
flat_fee_per_buy | number | 0 | flat fee some platforms add on small buys |
{"name": "crypto_trade_cost", "arguments": {"amount": 1000, "fee_pct": 0.6, "spread_pct": 0.5,
"network_fee_buy": 2.5, "network_fee_sell": 2.5, "weekly_buy": 25, "flat_fee_per_buy": 0.99}}
emergency_fund
Goal = monthly expenses x months to cover. Months to reach it, and the monthly amount needed to reach it by a target.
| Input | Type | Default | Notes |
|---|---|---|---|
monthly_expenses | number | required | must-pay expenses per month |
months_covered | integer | required | 1 to 60 |
saved | number | 0 | already saved |
monthly_add | number | 0 | added each month |
apy | number | 0 | savings APY, percent |
target_months | integer | 12 | reach the goal in this many months |
target_date | string | none | YYYY-MM or YYYY-MM-DD, instead of target_months |
{"name": "emergency_fund", "arguments": {"monthly_expenses": 2500, "months_covered": 3,
"saved": 500, "monthly_add": 300, "target_date": "2027-10"}}
Result (abridged): goal $7,500.00; 24 months to reach it at $300 a month; $583.33 a month reaches it in 12 months.
list_guides
No inputs. Returns the ten guides (title, subtitle, pages, what each covers, price), the complete set ($24.95 for all ten, 10 for the price of 5), the starter pack price (guides 1-3 only), and the guides link.
{"name": "list_guides", "arguments": {}}
Errors
Bad input never crashes the server. It returns:
{"error": {"type": "validation_error", "message": "Invalid input for credit_card_payoff.",
"details": [{"field": "apr", "message": "Field required"}]},
"disclaimer": "Education only. Not financial advice."}
Calculator link parameters (for the site)
calculator_url uses the site's own form field ids as query parameters, so the site can pre-fill
each form by reading ?name=value into the field with that id. Numbers are plain (5000, 24.99);
booleans are 1 or 0.
| Calculator page | Parameters |
|---|---|
/calculators/credit-card-payoff/ | balance, apr, minPct, minFloor, plusInterest, fixedPayment |
/calculators/debt-consolidation/ | d1b, d1r, d1p, d2b, d2r, d2p, d3b, d3r, d3p (balance, APR, payment per debt), loanApr, loanMonths, feePct |
/calculators/loan-term/ | amount, apr, termA, termB |
/calculators/crypto-trade-cost/ | amount, feePct, spreadPct, networkBuy, networkSell, weekly, freq, flatFee |
/calculators/emergency-fund/ | expenses, monthsCover, saved, monthly, apy, target |
Notes: unused debt rows are sent as dNb=0 so the form's example rows are not counted. With more
than 3 debts the link opens the plain page (the form has 3 rows) and the result says so. Some site
fields are dropdowns (loan terms, months to cover, target, frequency); a value outside the dropdown's
options needs the site to add that option or fall back to its default.
Development
pip install -e ".[dev]"
pytest
tests/test_calc.py is a port of the site's site/tests/calc-math.test.js (same hand-checked cases
and the same cross-checks), and tests/test_server.py awaits list_tools and call_tool directly.
License
MIT. The Real Cost by NoBanks Nearby.