generated: '2026-09-19'
method: derived
source: >-
  Derived by aligning the live MCP tools/list (probed anonymously 2026-09-19 at
  https://vouchspec.plyrium.com/api/vouchspec/v1/mcp, one tool with inputSchema) and the A2A skill list
  (a2a/plyrium-com-agent-card.json) with the provider-hosted OpenAPI 3.1 (openapi/plyrium-com-vouchspec-openapi.yml,
  8 operations). Nothing here is inferred - the MCP tool's own observed output is byte-equivalent to the REST
  discovery response.
purpose: >-
  VouchSpec deliberately splits its surface: MCP and A2A carry ONLY the free read-only discovery capability,
  and the paid purchase plus receipt verification live ONLY on REST (x402-gated POST + anonymous GETs). The
  crosswalk makes that split explicit so an agent knows which surface can actually complete the job.
surfaces:
  rest_openapi: openapi/plyrium-com-vouchspec-openapi.yml     # 8 operations, 4 schemas; anonymous except POST /validate (x402)
  mcp: https://vouchspec.plyrium.com/api/vouchspec/v1/mcp     # tools/list open (no auth); 1 tool
  a2a: https://vouchspec.plyrium.com/api/vouchspec/v1/a2a     # message/send open (no auth); 1 skill
  graphql: null
crosswalk:
- tool: get_vouchspec_discovery
  surface: mcp
  category: discovery
  rest: [getVouchSpecDiscovery]
  binding: rest
  confidence: high
  note: Observed structuredContent is the same schema_version 1.3.0 document GET /api/vouchspec/v1/discovery returns; inputSchema is an empty object on both sides.
- tool: discover_vouchspec_validation
  surface: a2a
  category: discovery
  rest: [getVouchSpecDiscovery]
  binding: rest
  confidence: high
  note: A2A skill; message/send returned the discovery document as a data part. Same backing operation as the MCP tool.
mcp_only: []
rest_only:
- category: discovery
  operations: [getVouchSpecHealth, getVouchSpecX402Manifest, getVouchSpecValidationService]
  reason: Health, x402 manifest and the GET side of /validate are REST-only; their content is folded into the discovery document the tool returns.
- category: purchase
  operations: [purchaseExactCommitValidation]
  reason: >-
    The only write operation. x402-paid (402 PAYMENT-REQUIRED challenge, retry with PAYMENT-SIGNATURE). Discovery
    states mcp.paid_execution_available false and a2a.paid_execution_available false - purchase is REST-only by design.
- category: verification
  operations: [getVouchSpecIssuerKey, getVouchSpecReceipt, getVouchSpecReceiptStatus]
  reason: Receipt bytes, live status and the Ed25519 issuer key are anonymous REST GETs with no MCP or A2A equivalent.
coverage:
  mcp_tools_named: 1
  mcp_tools_bound: 1
  a2a_skills_named: 1
  a2a_skills_bound: 1
  mcp_only: 0
  rest_operations_total: 8
  rest_operations_with_tool: 1
  rest_operations_without_tool: 7