generated: '2026-08-13'
method: probed
source: https://mcp.b12.io/mcp
note: >-
  Cross-cutting semantics for B12's only machine-callable surface, the MCP
  server. There is no REST API, so there is no HTTP resource convention to
  record — the conventions here are JSON-RPC and MCP transport conventions,
  established by live probe.

surface:
  kind: mcp
  protocol: JSON-RPC 2.0 over Streamable HTTP
  protocol_version: '2025-06-18'
  endpoints:
  - https://mcp.b12.io/mcp
  - https://b12.io/mcp
  rest: none
  graphql: none
  webhooks: none

authentication:
  style: none
  detail: anonymous; no key, no token, no OAuth challenge
  see: authentication/b12-authentication.yml

content_negotiation:
  accept_required: 'application/json, text/event-stream'
  enforced: true
  on_violation: JSON-RPC -32600, HTTP 406 on GET / HTTP 200 on a partial Accept
  response_content_type:
    mcp.b12.io: text/event-stream (SSE frames)
    b12.io: application/json
  note: >-
    The two deployments disagree on response media type for an identical
    request. A client hard-coded to parse one will fail against the other.

idempotency:
  supported: false
  header: null
  scope: null
  retention: null
  evidence: >-
    The generate_website tool description states: "To create a separate,
    additional website, call the tool again." Its annotations set
    readOnlyHint false and destructiveHint false. A repeated call with identical
    arguments produces an additional website draft, not the original one.
  agent_impact: >-
    There is no safe retry. An agent that retries after a timeout or a dropped
    SSE stream cannot tell whether the first call landed, and will create a
    duplicate draft. No idempotency key is accepted and no request
    de-duplication is documented.
  note: >-
    Recorded as an explicit NO. No Idempotency pointer is emitted in apis.yml,
    because the provider does not offer idempotency on this surface.

pagination:
  supported: false
  note: >-
    tools/list, resources/list and prompts/list each return a complete array
    with no nextCursor. The MCP cursor pagination mechanism is unused, which is
    unremarkable at one tool and one resource.

versioning:
  scheme: mcp-protocol-negotiation
  protocol_version: '2025-06-18'
  server_version: 1.26.0
  detail: >-
    initialize echoes protocolVersion 2025-06-18 and serverInfo
    {name: b12-mcp-server, version: 1.26.0}. Version is discovered by
    handshake, not by URL path or header. There is no /v1/ in the endpoint.
  published_policy: none
  see: lifecycle/b12-lifecycle.yml

request_tracing:
  request_id_header: null
  correlation: JSON-RPC `id` echoed on success
  caveat: >-
    On transport-level errors the server does NOT echo the id — it substitutes
    the literal string "server-error", so a failed request cannot be correlated
    back by id.

error_envelope:
  shape: JSON-RPC 2.0 error object
  rfc9457: false
  see: errors/b12-problem-types.yml

rate_limit_signaling:
  headers: none
  detail: no X-RateLimit-*, no RateLimit-*, no Retry-After observed
  see: rate-limits/b12-rate-limits.yml

metadata_and_expansion:
  metadata: >-
    Tools carry an MCP `_meta` block. mcp.b12.io uses `_meta.ui` to bind an
    MCP-UI resource; b12.io uses `openai/outputTemplate` and
    `openai/toolInvocation` hints for ChatGPT Apps.
  field_expansion: not applicable
  sparse_fields: not applicable

side_effects:
  note: >-
    generate_website is a WRITE. It provisions a website draft on B12
    infrastructure and returns a static preview plus a signup link. It is
    reachable with no credential, so an anonymous caller can cause B12-side
    resource creation. openWorldHint is false — the tool does not reach beyond
    B12's own domain.

x-evidence:
  fetched: '2026-08-13'
  probes:
  - {url: 'https://mcp.b12.io/mcp', method: 'POST initialize', http_status: 200}
  - {url: 'https://mcp.b12.io/mcp', method: 'POST tools/list', http_status: 200}
  - {url: 'https://mcp.b12.io/mcp', method: 'POST resources/list', http_status: 200}
  - {url: 'https://mcp.b12.io/mcp', method: 'POST prompts/list', http_status: 200, result: empty array}
  - {url: 'https://b12.io/mcp', method: 'POST tools/list', http_status: 200}