How I Fixed Claude's Math Problem with 100 Lines of MCP Code
LLMs are great at explaining math. They're inconsistent at doing math. Ask Claude to calculate a 30-year mortgage on $400,000 at 6.5% APR twice. You might get $2,528 and $2,533 in the same session....
Source: DEV Community
LLMs are great at explaining math. They're inconsistent at doing math. Ask Claude to calculate a 30-year mortgage on $400,000 at 6.5% APR twice. You might get $2,528 and $2,533 in the same session. The correct answer is $2,528.27. This is not a hallucination bug you can prompt your way out of. It's an architecture problem. LLMs are probabilistic text generators — arithmetic is deterministic. The fix is MCP: give the LLM a structured tool that always returns the right number. Here's how to do it in under 10 minutes. What You're Building A connection between Claude Desktop and a calculator server that exposes 7 tools: mortgage, TDEE, compound interest, BMI, loan payoff, percentage, and age. When you ask "what's my mortgage payment?", Claude calls calculate_mortgage instead of guessing. Always correct. Always the same. Step 1: Install npx -y @thicket-team/mcp-calculators No npm install needed. npx -y handles everything. Step 2: Configure Claude Desktop Open your config file: Mac: ~/Librar
