# By protocol · Integra

> Where the ATR hash rides in x402, MPP, ACP, UCP, AP2, ACK, Visa TAP, Verifiable Intent, A2A and MCP.

URL: https://integraledger.com/protocols

By protocol

## The agreement rides the protocols agents already speak.

Each protocol below is someone else’s work. Each page says, in the standard’s and the package’s words, where the ATR hash rides in it, what the buyer signs, and what a payment through it proves. [Source: LCP Appendix C⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#appendix-c-protocol-integration-illustrations) · [Source: lcp docs: agentic checkouts⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/checkouts.md)

**Sources (2)**

[LCP Appendix C⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#appendix-c-protocol-integration-illustrations) · [lcp docs: agentic checkouts⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/checkouts.md)

1. [x402 Payment over HTTP 402 The seller’s 402 challenge carries the ATR hash and a link to the ATR; the payment carries the ATR hash in the rail’s own field. 29 pairings in @integraledger/lcp](https://integraledger.com/protocols/x402)
2. [MPP Machine Payments Protocol The MPP challenge itself carries the ATR hash: its id is derived from it, so whatever the payer signs over the challenge commits to it. 26 pairings in @integraledger/lcp](https://integraledger.com/protocols/mpp)
3. [ACP Agentic Commerce Protocol The checkout session’s id is the ATR hash, with the link to the ATR in the session’s metadata. 2 pairings in @integraledger/lcp](https://integraledger.com/protocols/acp)
4. [UCP Universal Commerce Protocol A `legal_context` link in the checkout carries the ATR hash, before the business signs the checkout. 4 pairings in @integraledger/lcp](https://integraledger.com/protocols/ucp)
5. [AP2 Agent Payments Protocol The merchant-signed checkout carries the ATR hash, and the buyer’s Checkout Mandate commits to that checkout. 1 pairings in @integraledger/lcp](https://integraledger.com/protocols/ap2)
6. [ACK Agent Commerce Kit The seller-signed Payment Request takes the ATR hash as its id. 1 pairings in @integraledger/lcp](https://integraledger.com/protocols/ack)
7. [Visa TAP Trusted Agent Protocol The agent’s payer signature covers a field holding the ATR hash. 1 pairings in @integraledger/lcp](https://integraledger.com/protocols/visa-tap)
8. [Verifiable Intent Mastercard Verifiable Intent A Verifiable Intent mandate signs the hash of a checkout that carries the ATR hash. 2 pairings in @integraledger/lcp](https://integraledger.com/protocols/mastercard-vi)
9. [A2A Agent2Agent protocol A2A delivers the ATR hash and a link to the ATR with the task; the payment for the task carries the ATR hash in its own pairing. delivery, no pairing](https://integraledger.com/protocols/a2a)
10. [MCP Model Context Protocol MCP delivers legal context to agents as tools, whatever protocol the payment uses. delivery, no pairing](https://integraledger.com/protocols/mcp)

[Every payment type in the package: where the ATR hash rides, and what each proves](https://integraledger.com/payment-types)