generated: '2026-09-05'
method: derived
source: mcp/4th-heart-mcp-tools.json
note: >-
  Derived from the probed MCP tool set and the UCP capability declarations, not from an OpenAPI —
  there is none. Entities are named only where a tool operates on them by name; relationships are the
  ones UCP declares via capability `extends`, plus the id references the tool schemas require. Field
  lists are deliberately absent: the tool inputSchemas describe request envelopes, and no response
  schema is published, so enumerating attributes would be invention.
entities:
- name: product
  identified_by: identifier
  operations: [get_product, lookup_catalog, search_catalog]
  note: Catalog unit. lookup_catalog resolves products or variants by identifier.
- name: variant
  identified_by: identifier
  operations: [lookup_catalog]
  note: Named in the lookup_catalog description as an alternative identifier target for a product.
- name: cart
  identified_by: id
  operations: [create_cart, get_cart, update_cart, cancel_cart]
- name: checkout
  identified_by: id
  operations: [create_checkout, get_checkout, update_checkout, complete_checkout, cancel_checkout]
- name: order
  identified_by: id
  operations: [get_order]
  note: Read-only on this surface. No tool creates, amends or refunds an order.
- name: agent_profile
  identified_by: meta.ucp-agent.profile
  operations: []
  note: >-
    A URI the caller supplies and the server dereferences on tools/call. Not addressable by any tool,
    but it is a required entity in every mutating request.
relationships:
- from: cart
  to: product
  kind: has_many
  via: line items
  confidence: high
  evidence: >-
    UCP declares dev.ucp.shopping.cart alongside the catalog service; cart tools operate on line
    items per the checkout tool descriptions
- from: checkout
  to: cart
  kind: belongs_to
  via: cart id
  confidence: medium
  evidence: >-
    dev.ucp.shopping.fulfillment and .discount both declare extends [dev.ucp.shopping.checkout,
    dev.ucp.shopping.cart] in /.well-known/ucp, which binds the two
- from: checkout
  to: product
  kind: has_many
  via: line items
  confidence: high
  evidence: >-
    'Returns details about the checkout, including line items, totals, and any applicable discounts
    or taxes' — get_checkout description
- from: order
  to: checkout
  kind: belongs_to
  via: completion of complete_checkout
  confidence: high
  evidence: complete_checkout 'Completes a checkout and returns the checkout result'
capabilities_declared:
- dev.ucp.shopping.cart
- dev.ucp.shopping.checkout
- dev.ucp.shopping.order
- dev.ucp.shopping.discount
- dev.ucp.shopping.fulfillment
money:
  representation: integer minor units plus ISO 4217 currency code
  evidence: stated in every tool description