4th & Heart

4th & Heart Agentic Commerce (UCP / MCP)

The agent-facing commerce surface of the 4th & Heart online store, implemented by Shopify's native Universal Commerce Protocol support on the merchant's own domain. A remote MCP server at https://fourthandheart.com/api/ucp/mcp answers tools/list anonymously with 13 tools covering catalog search and lookup, cart lifecycle, checkout lifecycle and order retrieval. The UCP merchant profile at /.well-known/ucp declares protocol version 2026-08-25 with two prior dated versions still served, and the shopping, cart, checkout, fulfillment, discount and order capabilities. Checkout completion requires contemporaneous buyer approval.

GitHub

Documentation

📖
Authentication
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/authentication/4th-heart-authentication.yml
📖
RateLimits
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/rate-limits/4th-heart-rate-limits.yml

Other Resources

🔗
MCPServer
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/mcp/4th-heart-mcp.yml
🔗
OAuthScopes
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/scopes/4th-heart-scopes.yml
🔗
ErrorCatalog
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/errors/4th-heart-problem-types.yml
🔗
Conventions
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/conventions/4th-heart-conventions.yml
🔗
DataModel
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/data-model/4th-heart-data-model.yml
🔗
APIsJSON
https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/apis.yml

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API entry from apis.yml

apis.yml Raw ↑ 
aid: 4th-heart:4th-heart-commerce
name: 4th & Heart Agentic Commerce (UCP / MCP)
description: The agent-facing commerce surface of the 4th & Heart online store, implemented by Shopify's
  native Universal Commerce Protocol support on the merchant's own domain. A remote MCP server at https://fourthandheart.com/api/ucp/mcp
  answers tools/list anonymously with 13 tools covering catalog search and lookup, cart lifecycle, checkout
  lifecycle and order retrieval. The UCP merchant profile at /.well-known/ucp declares protocol version
  2026-08-25 with two prior dated versions still served, and the shopping, cart, checkout, fulfillment,
  discount and order capabilities. Checkout completion requires contemporaneous buyer approval.
image: https://fourthandheart.com/cdn/shop/files/4thandHeartGhee.png?v=1730292913
humanURL: https://fourthandheart.com/agents.md
baseURL: https://fourthandheart.com/api/ucp/mcp
tags:
- Agentic Commerce
- MCP
- Universal Commerce Protocol
- E-Commerce
- Catalog
- Cart
- Checkout
tags_raw:
- Agentic Commerce
- Model Context Protocol
- Universal Commerce Protocol
- E-Commerce
- Catalog
- Cart
- Checkout
properties:
- type: MCPServer
  url: mcp/4th-heart-mcp.yml
- type: Authentication
  url: authentication/4th-heart-authentication.yml
- type: OAuthScopes
  url: scopes/4th-heart-scopes.yml
- type: ErrorCatalog
  url: errors/4th-heart-problem-types.yml
- type: Conventions
  url: conventions/4th-heart-conventions.yml
- type: DataModel
  url: data-model/4th-heart-data-model.yml
- type: RateLimits
  url: rate-limits/4th-heart-rate-limits.yml
x-surface: platform-generated
x-platform: shopify
x-platform-surface: ucp