4th & Heart

4th & Heart is a California-based consumer packaged goods company that makes grass-fed, pasture-raised ghee (clarified butter) and ghee-based spreads, sold direct-to-consumer from its own Shopify storefront at fourthandheart.com and through national grocery retail. It is not a software vendor and publishes no developer program, but the storefront exposes a real, unauthenticated agent-commerce surface: a Universal Commerce Protocol (UCP) merchant profile at /.well-known/ucp, a live Model Context Protocol server at /api/ucp/mcp serving 13 catalog, cart, checkout and order tools with full JSON Schema, an /llms.txt and /agents.md agent instruction document, and Shopify customer-account OAuth 2.0 / OpenID Connect discovery metadata on its own domain.

4th & Heart publishes 1 API on the APIs.io network. Tagged areas include Company, Food and Beverage, Consumer Packaged Goods, Retail, and E-Commerce.

4th & Heart’s developer surface includes documentation, engineering blog, support, signup flow, and 12 more developer resources.

🌐 Visit website 📡 Source on GitHub
25.4/100 emerging ▬ flat Agent 24/100 agent aware Front door AI 1/6 silent Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0
1 APIs 1 MCP Servers
CompanyFood and BeverageConsumer Packaged GoodsRetailE-CommerceAgentic CommerceUniversal Commerce ProtocolMCPShopifyDirect to Consumer

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-09-25 · rubric v0.23.0
Composite quality — 25.4/100 · emerging
Contract Quality 0.0 / 21
Developer Ergonomics 5.2 / 17
Access Clarity 5.8 / 17
Operational Transparency 0.0 / 11
Contract Governance 1.9 / 10
Discoverability 6.4 / 9
Regulatory Posture 5.1 / 15
Agent readiness — 24/100 · agent aware
Machine-Readable Contract 0 / 18
Agentic Access Contract 0 / 10
Documented Reversibility 0 / 6
MCP Server 12 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 7 / 7
Typed Event Surface 0 / 6
Agent Skills 5 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 0 / 4
Delegated User Identity 6 / 6
Protected Resource Metadata 5 / 5
Registration Without a Human 0 / 6
Agentic Commerce Well-Known Document 5 / 5
Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.
Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.
The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/4th-heart: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 1

Individual APIs this provider publishes, each with its own machine-readable definition.

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...

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

4th & Heart MCP Server

MCP SERVER

Pricing Plans 1

Published pricing tiers and plan structures.

4Th Heart Plans Pricing

0 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

4Th Heart Rate Limits

0 limits

RATE LIMITS

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

4Th Heart Authentication

none/oauth2/openIdConnect · 4 schemes

SECURITY

4Th Heart Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Scopes 1

OAuth scopes governing access to this provider's APIs.

4Th Heart Scopes

4 scopes · authorizationCode

4 scopes

SCOPES

Resources

Get Started 1

Portal, sign-up, and the first successful call

SignUp
SignUp

Documentation 1

Reference material describing how the API behaves

Documentation
Documentation

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt
LLMsTxt
 WellKnown
WellKnown
 MCPServer
MCPServer
 AgentSkill
AgentSkill

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

Conformance
Conformance
 Lifecycle
Lifecycle

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity

Operate 2

Status, limits, changes, and where to get help

RateLimits
RateLimits
 Support
Support

Commercial 3

Pricing, plans, and the legal terms of use

Plans
Plans
 TermsOfService
TermsOfService
 PrivacyPolicy
PrivacyPolicy

Company 2

The organization behind the API

Website
Website
 Blog
Blog

Source (apis.yml)

apis.yml Raw ↑ 
aid: 4th-heart
name: 4th & Heart
description: '4th & Heart is a California-based consumer packaged goods company that makes grass-fed, pasture-raised ghee
  (clarified butter) and ghee-based spreads, sold direct-to-consumer from its own Shopify storefront at fourthandheart.com
  and through national grocery retail. It is not a software vendor and publishes no developer program, but the storefront
  exposes a real, unauthenticated agent-commerce surface: a Universal Commerce Protocol (UCP) merchant profile at /.well-known/ucp,
  a live Model Context Protocol server at /api/ucp/mcp serving 13 catalog, cart, checkout and order tools with full JSON Schema,
  an /llms.txt and /agents.md agent instruction document, and Shopify customer-account OAuth 2.0 / OpenID Connect discovery
  metadata on its own domain.'
image: https://fourthandheart.com/cdn/shop/files/4thandHeartGhee.png?v=1730292913
url: https://raw.githubusercontent.com/api-evangelist/4th-heart/refs/heads/main/apis.yml
specificationVersion: '0.20'
created: '2026-09-05'
modified: '2026-09-05'
tags:
- Company
- Food and Beverage
- Consumer Packaged Goods
- Retail
- E-Commerce
- Agentic Commerce
- Universal Commerce Protocol
- MCP
- Shopify
- Direct to Consumer
tags_raw:
- Company
- Food and Beverage
- Consumer Packaged Goods
- Retail
- E-Commerce
- Agentic Commerce
- Universal Commerce Protocol
- Model Context Protocol
- Shopify
- Direct to Consumer
apis:
- 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
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://fourthandheart.com/
- type: Documentation
  url: https://fourthandheart.com/agents.md
- type: LLMsTxt
  url: llms/4th-heart-llms.txt
- type: WellKnown
  url: well-known/4th-heart-well-known.yml
- type: MCPServer
  url: mcp/4th-heart-mcp.yml
- type: Conformance
  url: conformance/4th-heart-conformance.yml
- type: Lifecycle
  url: lifecycle/4th-heart-lifecycle.yml
- type: DomainSecurity
  url: security/4th-heart-domain-security.yml
- type: Plans
  url: plans/4th-heart-plans-pricing.yml
- type: RateLimits
  url: rate-limits/4th-heart-rate-limits.yml
- type: AgentSkill
  url: skills/_index.yml
- type: Blog
  url: https://fourthandheart.com/blogs/recipes
- type: Support
  url: https://fourthandheart.com/pages/contact-us
- type: SignUp
  url: https://fourthandheart.com/account/login
- type: TermsOfService
  url: https://fourthandheart.com/policies/terms-of-service
- type: PrivacyPolicy
  url: https://fourthandheart.com/policies/privacy-policy
x-enrichment:
  date: '2026-09-05'
  status: enriched
  artifacts_added: 19
  pass: local-v3

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