CRA AGENT is an open-source payment rail that lets AI agents pay for the services they use, on Arc, Circle's USDC-native Layer 1. It implements the x402 HTTP payment standard: when an agent requests a paid API and the server answers 402 Payment Required, CRA AGENT reads the price and terms, checks the spending policy configured by the operator, verifies the seller, signs a USDC payment settled by Circle Gateway, retries the request and writes a receipt to a ledger. It ships as an MCP server, so any LLM client can use it as a tool, and as TypeScript libraries published on npm under the MIT license. Two payment rails are supported: gas-free batched nanopayments for pay-per-call APIs, and ERC-8183 escrow for larger jobs with an evaluator. On the selling side, two lines of code put a price on an API route and receive USDC on Arc.