{
  "slug": "compound-interest",
  "mcpServerUrl": "https://plugins-worker.demos.42a.ai/compound-interest/mcp",
  "interface": {
    "displayName": "Handy Compound Interest",
    "shortDescription": "Savings growth and goals",
    "longDescription": "See exactly how savings and investments grow with compound interest, and how much to save each month to hit a goal.\n\nEnter a starting amount, a monthly or yearly contribution, the annual rate and the number of years. Choose daily, monthly, quarterly or annual compounding, deposits at the start or end of each period, a yearly raise in your contributions, and an inflation rate to see the result in today's money. The card shows the final balance, how much you deposited versus how much interest earned, a chart of deposits vs growth and a year-by-year table. Drag the rate and years sliders to compare scenarios.\n\nSaving toward something? Give the target and the deadline to get the monthly amount needed, or the monthly amount to get how long it takes. Download the year-by-year table as an Excel workbook with live formulas. An illustration, not investment advice.",
    "category": "Finance",
    "defaultPrompt": [
      "If I invest $500 a month at 8% for 30 years, how much will I have?",
      "How much is $10,000 worth after 20 years at 7% compounded monthly?",
      "How much do I need to save each month to have $50,000 in 5 years?"
    ],
    "capabilities": [
      "Exact compound growth with daily, monthly, quarterly or annual compounding",
      "Monthly or yearly contributions, at the start or end of each period",
      "Yearly contribution raises and inflation-adjusted results",
      "Deposits vs growth chart and year-by-year table",
      "Monthly amount needed for a goal, or the time it takes",
      "Excel year-by-year table with live formulas"
    ],
    "logo": "https://plugins-worker.demos.42a.ai/compound-interest/icon.svg",
    "websiteURL": "https://plugins-worker.demos.42a.ai/compound-interest/",
    "supportURL": "https://plugins-worker.demos.42a.ai/support",
    "privacyPolicyURL": "https://plugins-worker.demos.42a.ai/privacy",
    "termsOfServiceURL": "https://plugins-worker.demos.42a.ai/terms",
    "developerName": "42a"
  },
  "keywords": [
    "compound interest calculator",
    "investment calculator",
    "savings calculator",
    "how much will my savings grow",
    "retirement savings calculator",
    "savings goal calculator",
    "how much to save each month",
    "future value calculator"
  ],
  "tools": [
    {
      "name": "calculate_compound_interest",
      "title": "Calculate compound interest",
      "annotations": {
        "readOnlyHint": true,
        "destructiveHint": false,
        "openWorldHint": false,
        "idempotentHint": true
      }
    },
    {
      "name": "savings_goal",
      "title": "Plan a savings goal",
      "annotations": {
        "readOnlyHint": true,
        "destructiveHint": false,
        "openWorldHint": false,
        "idempotentHint": true
      }
    }
  ],
  "dataSources": [],
  "review": {
    "positiveTestCases": [
      {
        "description": "A lump sum compounded monthly",
        "prompt": "How much is $10,000 worth after 20 years at 7% compounded monthly?",
        "tools_triggered": [
          "calculate_compound_interest"
        ],
        "expected_behavior": "$40,387.39, of which $30,387.39 is interest."
      },
      {
        "description": "Monthly investing for 30 years",
        "prompt": "If I invest $500 a month at 8% for 30 years, how much will I have?",
        "tools_triggered": [
          "calculate_compound_interest"
        ],
        "expected_behavior": "$745,179.72 from $180,000 of deposits ($565,179.72 of growth)."
      },
      {
        "description": "Annual compounding with inflation and raises",
        "prompt": "Start with $5,000, add $200 a month increasing 3% a year, 5% compounded annually for 10 years. What is it worth in today's money with 2.5% inflation?",
        "tools_triggered": [
          "calculate_compound_interest"
        ],
        "expected_behavior": "$43,118.65 after 10 years ($32,513.31 deposited), worth $33,684.22 in today's money."
      },
      {
        "description": "Monthly amount for a goal",
        "prompt": "I have $5,000 saved. How much do I need to save each month to have $50,000 in 5 years at 4.5%?",
        "tools_triggered": [
          "savings_goal"
        ],
        "expected_behavior": "$651.44 a month for 60 months."
      },
      {
        "description": "Time to reach a goal",
        "prompt": "I have $50,000 invested and add $1,000 a month at 7%. How long until I have $1 million?",
        "tools_triggered": [
          "savings_goal"
        ],
        "expected_behavior": "287 months (23 years 11 months)."
      }
    ],
    "negativeTestCases": [
      {
        "prompt": "What is the monthly payment on a $20,000 loan at 6% for 4 years?",
        "expected_behavior": "Does not call Handy Compound Interest: A loan payment, not savings growth."
      },
      {
        "prompt": "Which index fund should I buy for retirement?",
        "expected_behavior": "Does not call Handy Compound Interest: Investment product advice, nothing to calculate."
      },
      {
        "prompt": "What was $100 in 1980 worth in today's dollars?",
        "expected_behavior": "Does not call Handy Compound Interest: Historical inflation adjustment uses CPI data, not a compound interest projection."
      }
    ]
  }
}