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.

exact

50-digit Decimal precision. Money & rates serialized as strings — zero float drift.

transparent

Every result includes the formula used, the inputs, the unit, and edge-case notes.

agent-friendly

Uniform status/value/formula/inputs_used shape. Errors return actionable hints, never exceptions.

production-ready

stdio + HTTP transports, API-key auth, rate limiting, usage metering, structured logs, OTel.

11 tools

calculate_metric

14 SaaS/biz metrics: LTV, CAC, LTV:CAC, payback, churn, MRR growth, ARR, break-even, NRR, GRR, Rule of 40, magic number…

currency_convert

9 currencies; static offline table or live/historical ECB rates with graceful fallback.

business_days

Add/count/next/prev; US/UK/EU + any ISO country + custom holidays.

compound_growth

Future value, present value, CAGR; 7 compounding frequencies incl. continuous.

net_present_value

Discounted cash flow (NPV) of a cashflow series.

internal_rate_of_return

IRR via Newton + bisection fallback.

loan_amortization

Payment, totals, full schedule, extra-payment payoff.

depreciation

Straight-line, declining-balance, sum-of-years-digits.

batch_calculate

Many calculations in one request.

list_metrics

Discovery: every metric + required params.

health_check

Version, capabilities, status.

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).

Streamable-HTTP endpoint

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

~/.cursor/mcp.json (or a project's .cursor/mcp.json)

mcp.json

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

claude_desktop_config.json (Settings → Developer → Edit Config). Uses the mcp-remote bridge for remote HTTP.

claude_desktop_config.json

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

.vscode/mcp.json (or run “MCP: Add Server” in the Command Palette)

.vscode/mcp.json

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

~/.codeium/windsurf/mcp_config.json

mcp_config.json

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

Cline → MCP Servers → Configure (cline_mcp_settings.json)

cline_mcp_settings.json

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

Zed settings.json → context_servers

settings.json

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

Any Streamable-HTTP MCP client

config

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

Verify from a terminal

curl — live USD→JPY conversion

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

Cursor Claude Desktop VS Code (Copilot Agent) Windsurf Cline Zed Continue LibreChat any MCP SDK

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.

Free

25 calls / day
All 11 tools
Static FX only (no live/historical)
No batch_calculate
No API key needed

Use free endpoint

For evaluation & low-volume testing.

Starter Popular

$12/mo

5,000 calls / day
All 11 tools
Live + historical FX (ECB)
batch_calculate unlocked
API key + usage dashboard

Get Starter →

Best for a single production agent.

Pro

$39/mo

50,000 calls / day
Everything in Starter
Highest priority
Manage/cancel via billing portal
Email support

Get Pro →

For fleets & high-volume workloads.

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

After purchase — add your key

{
  "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

Run locally (stdio, the default MCP transport)

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

Register locally (stdio)

MCP client config

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

Example tool call → structured result

// 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.", ...]
}

⛭ Deploy: Docker image + Fly.io & Render blueprints included. HTTP transport supports API keys, rate limiting, and a /metrics usage endpoint.