I Built a Pay-Per-Call MCP Server — Here's What the Agent Payment Stack Actually Looks Like

I shipped coinopai-mcp two days ago. It's a local MCP server that gives any AI agent access to crypto intelligence — preflight checks, trade signals, risk state — for USDC micropayments on Base. What I didn't expect was how much the payment layer would teach me about where agent commerce is actually heading. The Stack Nobody Asked For (But Everyone Needs) If you're building agents in 2026, you're suddenly dealing with a protocol stack that didn't exist 12 months ago: MCP — how your agent talks t