I spent the last 30 days logging every MCP tool call I made across
Cursor, Claude Code, and Claude Desktop. Some surprises: 1. Read tool calls dominate by volume but tokens are tiny they're cheap. The cost spike comes from a handful of big calls (web search, image processing, large file reads). 2. ~14% of tool calls fail or timeout. They still cost something on the LLM side because the model already burned input tokens. 3. There's no native way in Cursor/Claude/Windsurf to see which project or which session caused the spend. You only see totals. 4. Per-agent attribution flips assumptions: "the Claude Code in my dev folder" vs. "the Cursor in my marketing folder" had a 7x cost delta for the same number of files touched. I turned the logger into a product (MCPSpend) and we're launching on
PH tomorrow. Free tier 25k calls/month if anyone wants to test:
npx --yes @mcpspend/proxy@latest init --key mcps_live_xxx Curious anyone else tracking their MCP spend manually? What's
your stack?