Disclosure: I work on distribution for PinkWallet, which is building an agentic payments product (mentioned once near the end, honestly, as one option in early access). Every claim about a protocol below links to that protocol's own docs, spec repo, or announcement, checked today. Short answer: Don't pick one protocol as "the" agent payment standard — pick based on what your agent is actually doing. If it's paying another service per API call or per piece of data, look at x402 (or MPP ,...