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MCP Loan Calculator in VS Code

Monthly payments and full amortization in one sentence. loan_payment returns the monthly payment and total interest for principal, rate and term, and loan_amortize returns the full schedule; the annuity formula is implemented exactly, a 0% rate is handled as straight-line division rather than producing NaN, and every amount passes the shared money formatter so the cents agree with a bank's.

No writes, no network: auto-approve both tools in agent mode and loan math becomes a zero-click sentence inside any refactor that touches a financing feature.

What you get in VS Code

You say	Tool
Monthly payment on a 320,000 mortgage at 5.5% over 25 years?	`loan_payment`
Amortize that loan and show year 3.	`loan_amortize`
Compare 15 vs 30 years at 6.2% on 200,000.	`loan_payment, twice`

The contract suite asserts the annuity arithmetic over real stdio against hand-computed values: a 320,000 loan at 5.5% over 25 years returns the same monthly payment to the cent in both tools, the amortization schedule's principal and interest columns sum to the payment on every row, and the final balance lands on zero.

Install it in VS Code

The file is .vscode/mcp.json, and the key inside it is servers.

Scope	Path
This workspace	`<workspace>/.vscode/mcp.json`
Every workspace	`the user profile mcp.json, opened by the MCP: Open User Configuration command`

If you also run Claude Desktop, the shortest path there is one click: loan-calculator.mcpb from the latest release opens as an extension, with no JSON and no terminal. VS Code reads its own config, so here it is:

// .vscode/mcp.json  (the key is "servers")
{
  "servers": {
    "loan-calculator": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-servers/servers/loan-calculator/dist/index.js"]
    }
  }
}

Or from a terminal:

code --add-mcp '{"name":"loan-calculator","command":"node","args":["/absolute/path/to/mcp-servers/servers/loan-calculator/dist/index.js"]}'

The node command above wants a built file. From a clone, once:

git clone https://github.com/theluckystrike/mcp-servers.git
cd mcp-servers && npm install
npm run build -w packages/mcp-license -w servers/loan-calculator

That writes servers/loan-calculator/dist/index.js, and its absolute path is the one argument the config needs.

The npm packages are not published yet, so the form below returns a 404 today. It is here because it is what the entry becomes the day the publish lands, with nothing else changed:

code --add-mcp '{"name":"loan-calculator","command":"npx","args":["-y","@theluckystrike/mcp-loan-calculator"]}'

VS Code asks you to confirm you trust the server and its capabilities before it starts. Nothing runs until you answer.

Nothing is published to npm yet, so the working install paths are the ones above: the .mcpb bundle from the latest release, a clone and build, or the hosted URL.

No install: the hosted endpoint

There is no hosted endpoint for this one yet. MCP Loan Calculator runs locally over stdio with the config above, which is also the only form in which it reads and writes files on your own disk. Thirty of the servers in this collection are served at https://mcp.zovo.one/mcp/<name> over MCP streamable HTTP; https://mcp.zovo.one/mcp/connect lists them and prints a ready URL for each.

VS Code notes worth knowing first

The top-level key is "servers", not "mcpServers". A config pasted from a Claude Desktop or Cursor README parses cleanly, contributes no servers, and gives you no error to read, which makes it the most expensive one-word mistake here. Alongside it an "inputs" array holds secrets. The newer Agent Host reads a workspace .mcp.json instead.

Free: Everything: two tools, no metering, no key. Pro is $19 once, verified offline.

Questions

Why does my mcp.json do nothing?

The key is servers, not mcpServers. A config copied from a Claude Desktop README parses cleanly and contributes nothing. Rename it. On the newer Agent Host, use a workspace .mcp.json instead.

Do I have to edit the file at all?

No. code --add-mcp takes the server object on the command line, and MCP: Add Server in the palette asks whether the target is Workspace or Global.

Where do the MCP Loan Calculator tools show up?

In Chat, behind the tools picker, once the server has started. Adding or changing one raises a prompt asking you to confirm you trust it; if the picker is empty, that prompt is usually still waiting.

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