LLMs are shockingly bad at arithmetic. Ask an agent to chain a CAC payback with a churn-adjusted LTV, convert it to EUR, and discount three years of cash flows, and you will get an answer that looks right and is quietly wrong. Floating point, dropped steps, and confident hallucination are a bad combination when the output is a number someone makes a decision on.
So I built PrecisionCalc MCP — a deterministic Model Context Protocol server that gives AI agents a calculator they can actually trust. Every monetary/financial value is computed with arbitrary-precision decimals (never floats), and every response includes the exact value, the formula used, the inputs, the unit, and any assumptions — so the agent (and you) can audit it.
It's live, free to start, and takes about 30 seconds to add.
Add it to your agent
It's a remote server over Streamable HTTP — no install:
