Field notes
Read before you build.
Short, practical guides for providers and agent developers. Protocol mechanics, tool design, pricing and the essential data that agents actually pay for.
x402 in 60 seconds
The HTTP 402 payment flow, the headers, the facilitator, and the most common misunderstanding.
Best APIs for agent traffic
ZIP codes, IP intelligence, geocoding, weather and the operational data agents actually pay for, ranked by demand, moat and difficulty.
MCP server best practices
Transports, tool design, schemas, security and the mistakes that break real agents in production.
How x402 payments work, and where the money lands
A practical guide to receiving USDC, setting up a payout wallet, facilitator fees, and keeping the payment rail x402-only.
The agent-ready API checklist
Twenty requirements an API should meet before an autonomous agent pays for it.
Prefer machine-readable docs?
Every guide has a markdown twin, and the full catalogue is in llms.txt.