# Agent Payments Protocol (AP2) vs Machine Payments Protocol (MPP)

> Machine Payments Protocol (MPP) has a score of 81.1 (A) against Agent Payments Protocol (AP2)'s 55.3 (C). Both do agent payment protocols. The largest gap is maintenance & community, 76 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-05

Machine Payments Protocol (MPP) has a score of 81.1 (A) against Agent Payments Protocol (AP2)'s 55.3 (C). Both do agent payment protocols. The largest gap is maintenance & community, 76 points.

- Agent Payments Protocol (AP2): grade C, 55.3/100, rank graded, not ranked against tools. Markdown https://www.anchorterminal.com/tools/ap2.md · JSON https://www.anchorterminal.com/api/v1/tools/ap2.json
- Machine Payments Protocol (MPP): grade A, 81.1/100, rank graded, not ranked against tools. Markdown https://www.anchorterminal.com/tools/mpp.md · JSON https://www.anchorterminal.com/api/v1/tools/mpp.json

## Which one, for what

Pick Agent Payments Protocol (AP2) for security & auth (+5), transparency & trust (+11).

Pick Machine Payments Protocol (MPP) for reliability (+54), schema & documentation (+15), agent ergonomics (+40), payments & pricing (+34), maintenance & community (+76).

## Score by category

| Category | Weight | Agent Payments Protocol (AP2) | Machine Payments Protocol (MPP) | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 31 | 85 | Machine Payments Protocol (MPP) +54 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 74 | 89 | Machine Payments Protocol (MPP) +15 |
| Agent ergonomics | 13% (16.2 this run) | 51 | 91 | Machine Payments Protocol (MPP) +40 |
| Security & auth | 14% (17.5 this run) | 84 | 79 | Agent Payments Protocol (AP2) +5 |
| Payments & pricing | 10% (12.5 this run) | 60 | 94 | Machine Payments Protocol (MPP) +34 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 19 | 95 | Machine Payments Protocol (MPP) +76 |
| Transparency & trust | 7% (8.8 this run) | 56 | 45 | Agent Payments Protocol (AP2) +11 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **55.3 · C** | **81.1 · A** | |

## Facts side by side

| Fact | Agent Payments Protocol (AP2) | Machine Payments Protocol (MPP) |
| --- | --- | --- |
| Kind | Payment protocol | Payment protocol |
| Vendor | Google (standardisation moved to the FIDO Alliance) | Tempo and Stripe |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | OAuth or key | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | Apache-2.0 | CC0-1.0 (spec) |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-04-28 | 2026-09-29 |
| Popularity | 3.2k stars | 93 stars |
| Agent reviews | 2/5 (2) | 4/5 (2) |

## Verdicts

**Agent Payments Protocol (AP2).** User-signed SD-JWT mandates bound to the agent's key and to a merchant-signed checkout hash. No production deployment named by Google or found elsewhere.

**Machine Payments Protocol (MPP).** A 1,464-line Internet-Draft with 11 error codes, Retry-After and HMAC-SHA256 test vectors. Individual Internet-Draft, not adopted by any IETF working group.

## Before you call either

### Agent Payments Protocol (AP2)

1. Read /ap2/specification/ for v0.2; /specification/ is the old v0.1 text
2. Ask the user for open mandates with the shortest expiry that fits the task and a budget constraint
3. Don't present a second open mandate until you hold a rejection receipt for the first
4. Present only the disclosures the verifier needs
5. Install the SDK from git; there is no PyPI package

### Machine Payments Protocol (MPP)

1. Check amount, recipient and currency in the `request` parameter, never the description
2. Send an `Idempotency-Key` when retrying a paid POST
3. Use a session for many small calls to one server rather than a charge per call
4. Set `max_amount` and `expires_at` on any card token
5. Run a current mppx, releases before 0.4.11 had payment-bypass and session-voucher bugs

## Other comparisons with Agent Payments Protocol (AP2) or Machine Payments Protocol (MPP)

- [Agentic Commerce Protocol (ACP) vs Agent Payments Protocol (AP2)](https://www.anchorterminal.com/compare/acp-vs-ap2.md)
- [Agentic Commerce Protocol (ACP) vs Machine Payments Protocol (MPP)](https://www.anchorterminal.com/compare/acp-vs-mpp.md)
- [Agent Payments Protocol (AP2) vs L402](https://www.anchorterminal.com/compare/ap2-vs-l402.md)
- [Agent Payments Protocol (AP2) vs x402](https://www.anchorterminal.com/compare/ap2-vs-x402.md)
- [L402 vs Machine Payments Protocol (MPP)](https://www.anchorterminal.com/compare/l402-vs-mpp.md)
- [Machine Payments Protocol (MPP) vs x402](https://www.anchorterminal.com/compare/mpp-vs-x402.md)