Skip to content
11 protocols supported

Protocol Compatibility Matrix

The first multi-protocol payment bridge for AI agent commerce

AgenticMCPStores supports 11 protocols: 3 in production (ACP, AP2, AG-UI), 6 coming soon (VIC, KYApay, PayPal, MCAP, x402, UCP), plus MCP, A2A, and WebMCP. AG-UI enables real-time human-in-the-loop checkout with cryptographic confirmation. Merchants enable the protocols they need; agents pick the one they support. The Protocol Router handles detection, normalization, and settlement automatically.

17Total protocols
11In production
5Sandbox
9Layers
ProductionSandboxComing Soon
0

Layer 0 Structured Web Access

Discovery and data access layer for agent navigation

3 protocols
WebMCPW3C CG Draft (27 Mar 2026)
Production
W3C Community Group

W3C Community Group standard for agent-to-web interactions via browser APIs

B2BB2CD2C
DiscoveryW3C Standard
llms.txt
Production
Jeremy Howard / Answer.AI

Machine-readable format for LLM agent discovery and capabilities

B2BB2CD2C
Discovery
NLWeb
Production
Microsoft (R.V. Guha)

Open protocol and tools for building conversational interfaces for any website using Schema.org, MCP and LLMs

B2CD2C
MCP ToolDiscoverySSE
1

Layer 1 Agent-to-Tool Infrastructure

Core tool integration protocol with standardized JSON-RPC 2.0 interface

1 protocol
Model Context Protocol1.27.1
Production
Anthropic

Open standard for agent tool integration with standardized JSON-RPC 2.0 interface and tool registration

B2BB2CD2C
MCP ToolDiscovery
2

Layer 2 Agent-to-Agent Coordination

Multi-agent messaging, task orchestration and interoperability

1 protocol
A2A Protocol
Production
Google / Linux Foundation

Open protocol enabling AI agents to discover each other, negotiate communication formats, and coordinate tasks across vendors and platforms

B2BB2C
SSEDiscovery
3

Layer 3 Agent-to-User Interaction

Real-time human-in-the-loop flows with state sync and cryptographic confirmation

2 protocols
AG-UI Protocol
Production
CopilotKit

Open, event-based protocol that standardizes how AI agents connect to user-facing applications with streaming, state patches and tool calls

B2BB2CD2C
SSEDiscovery
A2-UI Protocolv0.8
Coming Soon
Google

Agent-to-UI: AI agents request rich, interactive, declarative JSON UI surfaces directly from MCP tools. Pass 'a2ui: true' in tool parameters to receive structured UI components (carousels, cards, forms) instead of plain JSON

B2BB2CD2C
MCP ToolDiscovery
4

Layer 4 Commerce Discovery & Checkout

Multi-protocol payment initiation and checkout flows for agentic commerce

3 protocols
ACP2026-01-30
Production
OpenAI + Stripe

Open standard for programmatic commerce flows between buyers, AI agents, and businesses with session resume and display context

B2BB2C
MCP ToolDiscovery
AP2
Production
Google

Open, non-proprietary protocol for secure, auditable AI agent payments using cryptographically-signed Mandates with support for cards, stablecoins and real-time transfers

B2C
MCP ToolDiscovery
UCPPhase B
Production
Google + Shopify et al.

Universal open-source standard for agentic commerce built on REST and JSON-RPC with native A2A, AP2 and MCP support, backed by 20+ global partners

B2BB2C
MCP ToolDiscovery
5

Layer 5 Human-Confirmed Payment Execution

W3C browser-native APIs that bridge agent-initiated checkout and settlement — requires a human present in the browser to confirm payment biometrically or via saved credentials

1 protocol
Payment Request APIW3C CR Draft (27 Jan 2026)
Production
W3C

W3C Candidate Recommendation standard that lets merchants accept Apple Pay, Google Pay and saved cards via a browser-native popup. Generates a Stripe PaymentMethod token processed by existing ACP / UCP adapters — zero PAN data stored, PCI DSS scope reduced. Complements fully-agentic flows; not used in headless x402 or MCAP paths.

B2CD2C
W3C Standard
6

Layer 6 Payments Authentication & Settlement

Tokenization and settlement protocols across fiat, stablecoin, and card networks

4 protocols
x4021.0
Production
Coinbase + Cloudflare

Internet-native payments standard built on HTTP 402 for USDC stablecoin micro-transactions between AI agents and APIs

B2BB2C
MCP ToolDiscovery
MCAP
Sandbox
Mastercard

Mastercard agentic tokenization via Stripe pass-through with RFC 9421 Ed25519 HTTP signatures and consent management

B2BB2C
MCP ToolDiscovery
VIC
Sandbox
Visa

Visa Identity Credentials with FIDO2 passkeys for tokenized payment flows and recurring subscriptions with trust score boost

B2BB2C
Discovery
PayPal
Sandbox
PayPal

PayPal Orders API v2 with agent settlements, subscriptions, invoicing and dispute resolution via @paypal/agent-toolkit

B2C
MCP ToolDiscovery
7

Layer 7 Trust & Identity Verification

Cryptographic identity proofs and passkey-based merchant verification

1 protocol
FIDO2 / WebAuthn
Sandbox
FIDO Alliance + W3C

Passwordless authentication standard with passkeys for merchant identity, 2FA and Digital Credentials API with mDL / SD-JWT-VC support

B2BB2C
DiscoveryW3C Standard
8

Layer 8 Shopper Context & Personalization

Preference sharing and shopper context across agents and retail platforms

1 protocol
SCP
Sandbox
Retail AI Council

Open standard letting shopper preferences, loyalty and behavioral intent travel safely across agents, channels and retail platforms

B2C
MCP ToolDiscovery

Why multi-protocol?

1

Agent choice

Agents pick the protocol they support. No negotiation, no fallback errors.

2

Revenue maximization

Do not lose sales because an agent only speaks x402 and your store only speaks ACP.

3

Future-proof

New protocols are added via the Plugin Registry. Your integration stays the same.

4

Single integration

One MCP endpoint, all protocols. The Protocol Router handles detection and routing.

Frequently asked questions

How many protocols can a merchant enable?

All supported protocols simultaneously. Currently ACP and AP2 are production-ready; VIC, KYApay, PayPal, and x402 are coming soon. The Protocol Router selects the best match based on agent capabilities and merchant priority configuration.

Is there a cost per protocol?

Protocol support is included in all tiers. Settlement fees depend on the protocol provider (Stripe for ACP, on-chain gas for x402, etc.).

Can I add a custom protocol?

Yes. The Plugin Registry supports custom adapters. Contact us for Enterprise integration support.

How does protocol detection work?

The Protocol Detector middleware inspects request headers, signatures, and body shape to identify the protocol with a confidence score (0.85-1.0). No manual configuration needed from the agent side.

Protocol Compatibility Matrix — AgenticMCPStores