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WealthSim

WealthSim MCP server

Let your AI assistant run WealthSim calculators and cite the source of every figure

What it is

MCP (Model Context Protocol) is the open standard that lets an AI assistant call tools. This server gives an assistant seven WealthSim calculators. Instead of estimating a figure from memory, the assistant sends your inputs to the same engines that power the calculators on this site and gets back the result, the data source and a link to the matching page.

It is free, read-only and needs no account or API key. The server does not store the inputs you send. Results are estimates for education, not financial advice; see the disclaimer and the methodology.

Endpoint

https://www.wealthsim.app/api/mcp

Transport: Streamable HTTP, stateless, no authentication. Every request is its own POST, so there is no session to keep. A GET in a browser sends you back to this page. Each IP address can make 60 requests a minute.

Tools and example prompts

  • sp500_historical_replay

    Replays what a lump sum and monthly contributions would have become in the S&P 500 between two calendar years (1928 to 2025), using real annual returns with dividends reinvested, and also in start-year dollars. Not a forecast.

    Try: What would $500 a month in the S&P 500 from 2000 to 2020 have become?

  • compound_interest

    Projects the future value of savings with monthly contributions at a fixed assumed annual return and optional annual fee, compounded monthly, before taxes.

    Try: I have $10,000 and add $200 a month. What do I have in 20 years at 7%?

  • retirement_how_long_money_lasts

    Estimates how long retirement savings last given a yearly withdrawal that grows with inflation: a steady-return view plus a test against real US market history.

    Try: Will $1,000,000 last if I withdraw $40,000 a year and keep 60% in stocks?

  • take_home_pay_us

    Net pay from an annual US salary for tax year 2026 after federal income tax, state income tax, Social Security, Medicare and an optional 401(k) deferral.

    Try: What is my take-home pay on $90,000 in California, filing single?

  • i_bond_value

    Current value, interest earned and cash-out value of a US Series I savings bond from its issue month and purchase amount, using the announced Treasury rates.

    Try: What is a $10,000 I bond bought in May 2022 worth now?

  • paro_es

    Calcula la prestación contributiva por desempleo en España (paro) a partir de la base de cotización, los días cotizados y los hijos a cargo. Responde en español.

    Try: ¿Cuánto paro me corresponde con una base de 1.800 euros y 720 días cotizados?

  • sueldo_neto_es

    Calcula el sueldo neto en España en 2026 desde el bruto anual: cotizaciónes a la Seguridad Social del trabajador y retención de IRPF según el algoritmo de la AEAT. Responde en español.

    Try: ¿Cuánto cobro neto al mes con 30.000 euros brutos en 14 pagas?

The S&P 500 replay uses annual returns from 1928 to 2025. The two Spanish tools answer in Spanish and use the 2026 rules.

Add it to your assistant

Menu names change between releases. If a step does not match what you see, check your client's current documentation for adding a remote MCP server by URL.

Claude

In Claude on the web or desktop, open Settings, then Connectors, and add a custom connector with the endpoint URL above. In Claude Code, run:

claude mcp add --transport http wealthsim https://www.wealthsim.app/api/mcp

ChatGPT

In ChatGPT, turn on developer mode in Settings, Connectors, Advanced, then create a connector that points to the endpoint URL with no authentication. Developer mode is available on some paid plans only.

Cursor

Add the server to ~/.cursor/mcp.json (or .cursor/mcp.json in a project):

{
  "mcpServers": {
    "wealthsim": {
      "url": "https://www.wealthsim.app/api/mcp"
    }
  }
}

Protocol

The server follows the 2026-07-28 MCP specification and also answers clients that speak the 2025 stateless Streamable HTTP. Browser-based clients can connect: the endpoint allows cross-origin requests and sets no cookies.