# Loan Calculate — REST API endpoint `loan-calculate`

Amortise a fixed-rate loan and show the impact of an optional monthly extra payment on payoff time and total interest.

- Category: finance
- MCP server: https://mcp.findutils.com/ (Streamable HTTP, no API keys, 120 req/min per IP)
- REST endpoint: POST https://api.findutils.com/api/tools/loan-calculate/execute (no API keys, 60 req/min per IP)
- Reference page: https://findutils.com/api/loan-calculate/
- Same tool on the other surface: https://findutils.com/mcp/loan-calculate/

## Call the endpoint (verified example)

```bash
curl -X POST https://api.findutils.com/api/tools/loan-calculate/execute \
  -H "Content-Type: application/json" \
  -d '{
    "principal": 10000,
    "annual_rate": 0.05,
    "years": 5
  }'

# Parameter schema
curl https://api.findutils.com/api/tools/loan-calculate
```

## Input schema

| Argument | Type | Required | Description |
|---|---|---|---|
| `principal` | number | yes | Loan balance. |
| `annual_rate` | number | yes | Annual interest rate as a decimal. |
| `years` | number | yes | Contract length in years. |
| `extra_payment` | number | no | Optional monthly extra paid on top of the standard payment. |

Example arguments (verified):

```json
{
  "principal": 10000,
  "annual_rate": 0.05,
  "years": 5
}
```

OpenAPI 3.1 spec: https://findutils.com/api/openapi.json · Interactive docs: https://findutils.com/api/docs/

## Also an MCP tool

```bash
claude mcp add findutils --transport http https://mcp.findutils.com/
```

Then ask the client to call `findutils:loan_calculate`. Full MCP reference: https://findutils.com/mcp/loan-calculate/

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