PrecisionCalc MCP

Why it exists

LLMs lose precision and hallucinate on multi-step financial formulas, currency conversions, business-day logic, and growth math. PrecisionCalc gives agents a trustworthy calculator with a consistent, parseable JSON envelope on every call.

11 tools

USDEURGBPJPY CADAUDCHFCNYINR

Add PrecisionCalc to your agent

One remote endpoint, no install, no API key. Pick your client, copy the config, restart. Same exact-Decimal engine as the Python build (verified 17/17 output parity).

https://precisioncalc-mcp.pages.dev/mcp

{
  "mcpServers": {
    "precisioncalc": {
      "url": "https://precisioncalc-mcp.pages.dev/mcp"
    }
  }
}

{
  "mcpServers": {
    "precisioncalc": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://precisioncalc-mcp.pages.dev/mcp"]
    }
  }
}

{
  "servers": {
    "precisioncalc": {
      "type": "http",
      "url": "https://precisioncalc-mcp.pages.dev/mcp"
    }
  }
}

{
  "mcpServers": {
    "precisioncalc": {
      "serverUrl": "https://precisioncalc-mcp.pages.dev/mcp"
    }
  }
}

{
  "mcpServers": {
    "precisioncalc": {
      "type": "streamableHttp",
      "url": "https://precisioncalc-mcp.pages.dev/mcp"
    }
  }
}

{
  "context_servers": {
    "precisioncalc": {
      "source": "custom",
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://precisioncalc-mcp.pages.dev/mcp"]
    }
  }
}

{
  "mcpServers": {
    "precisioncalc": {
      "type": "http",
      "url": "https://precisioncalc-mcp.pages.dev/mcp"
    }
  }
}

Verify from a terminal

curl -sN https://precisioncalc-mcp.pages.dev/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"currency_convert","arguments":{"amount":1000,"from_currency":"USD","to_currency":"JPY","live":true}}}'

Works with

Hosted vs. self-hosted — what you're paying for

The PrecisionCalc engine is open-source (MIT) and free to run yourself — paid plans buy the hosted convenience, not the algorithm. It's the same deterministic engine either way.

Run it yourself right now: npx -y precisioncalc-mcp — or deploy your own copy on Cloudflare Pages / Node / Deno / Bun. What you pay us for is not having to.

Pricing

Start free to evaluate. When your agent needs real volume, upgrade in two clicks — pay with card, get an API key instantly, send it as X-API-Key. Cancel anytime.

Secure checkout by Stripe · cards & wallets · promo codes supported · manage anytime at the billing portal. Prices in USD.

{
  "mcpServers": {
    "precisioncalc": {
      "url": "https://precisioncalc-mcp.pages.dev/mcp",
      "headers": { "X-API-Key": "pck_live_your_key_here" }
    }
  }
}

Prefer to self-host? The full Python server (stdio + HTTP), Docker image, and Fly.io / Render blueprints are open-source (MIT) — run your own with unlimited calls and your own keys.

Quickstart

git clone https://github.com/inity13/precisioncalc-mcp
cd precisioncalc-mcp
pip install -r requirements.txt

python server.py            # stdio
python server.py http       # streamable HTTP on /mcp

{
  "mcpServers": {
    "precisioncalc": {
      "command": "python",
      "args": ["/path/to/precisioncalc-mcp/server.py"]
    }
  }
}

// call: net_present_value
{ "rate": 0.10,
  "cashflows": [-10000, 3000, 4200, 6800] }

// result
{
  "status": "success",
  "value": "1307.287...",
  "formatted_value": "$1,307.29",
  "formula": "NPV = sum(CF_t / (1 + rate)^t)",
  "inputs_used": { "rate": "0.10", "cashflows": [...] },
  "unit": "USD",
  "notes": ["Period 0 cashflow is not discounted.", ...]
}

Built for correctness

49 unit tests plus Hypothesis property tests assert rounding invariants and inverse operations (PV↔FV round-trips, currency round-trips, loan total consistency, NPV(IRR)≈0). The calculation engines are pure and deterministic.