generated: '2026-09-03'
method: searched
source: https://developers.kudosity.com/reference/ (api-overview section) + both OpenAPI documents
authentication:
  v2:
    style: api key
    location: header
    parameter: x-api-key
  v1:
    style: http basic
    value: base64(api_key:api_secret)
  docs: https://developers.kudosity.com/reference/authentication
  note: API secret is a user-chosen value set on the account SETTINGS page, not issued by Kudosity.
idempotency:
  supported: false
  coverage: none
  evidence: No idempotency key header, parameter or documentation in either OpenAPI or the docs.
  note: 'For a messaging API this is a real agent-safety gap: a retried send is a second billable message.
    v2 offers message_ref for reconciliation after the fact, but it is not a de-duplication key.'
pagination:
  style: page-number
  request_params:
  - page
  - max
  response_block: 'page: {count, number}'
  defaults:
    page: 1
    max: 10
  max_page_size: 100
  docs: https://developers.kudosity.com/reference/pagination
  applies_to: Transmit SMS API (v1)
rate_limiting:
  limit: 15 requests/second/account
  status: 429
  code: OVER_LIMIT
  retry: none — throttled message requests are dropped, not retried
  negotiable: yes, on request
  headers: null
  docs: https://developers.kudosity.com/reference/rate-limiting
timestamps:
  format: ISO 8601
  timezone: UTC always
  note: v2 schemas use RFC 3339 date-time (e.g. 2025-08-26T10:30:00Z).
  docs: https://developers.kudosity.com/reference/timestamps
content_negotiation:
  v2: JSON only
  v1: JSON or XML (.json / .xml path suffix)
  docs: https://developers.kudosity.com/reference/requests
versioning:
  scheme: separate hosts + uri path
  v2: https://api.transmitmessage.com/v2/...
  v1: https://api.transmitsms.com/<action>.json
error_envelope:
  v2: RFC 9457 application/problem+json
  v1: 'error: {code, description}'
webhook_security:
  signature_header: x-transmitsms-signature
  algorithm: HMAC-SHA256 over the JSON-encoded callback params, keyed by the account API secret
  ordering: parameters must be hashed in the exact order they appear in the callback
  docs: https://developers.kudosity.com/docs/validating-webhook-signatures-from-kudosity
request_tracing:
  supported: false
  note: No request-id / correlation-id header documented on either API.
message_reference:
  field: message_ref
  api: v2
  purpose: caller-supplied reference returned alongside the Kudosity message id
reversibility:
  generated: '2026-09-03'
  method: derived
  source: openapi/kudosity-sms-api-openapi.yml + openapi/kudosity-webhook-api-openapi.yml + https://developers.kudosity.com/reference/post_cancel-sms-json
  grade: documented
  summary: 'Partial. The one consequential action with a real reversal path is a SCHEDULED v1 SMS send:
    POST /cancel-sms.json cancels it by message ID, and the docs state the window — scheduled messages
    only, before the send time. An immediate send on either API (SMS, MMS, WhatsApp, RCS) has no reversal:
    once accepted by the carrier a message cannot be recalled, and each send is billable. Configuration
    writes (webhooks, lists, contacts, keywords, leased numbers) are undoable via their own delete
    operations with no window limit.'
  write_surfaces:
  - action: v1 scheduled SMS send (POST /send-sms.json with send_at)
    reversal: POST /cancel-sms.json
    window: before the scheduled send time — the docs state scheduled messages can be cancelled using
      the message ID; an immediate or already-sent message cannot
    docs: https://developers.kudosity.com/reference/post_cancel-sms-json
    grade: documented
  - action: immediate message send — v2 POST /v2/sms, /v2/mms, /v2/whatsapp/messages, /v2/rcs/messages
      and v1 POST /send-sms.json without send_at
    reversal: none
    window: null
    grade: none
    note: 'irreversible and billable: no recall, void or refund operation exists on either API.'
  - action: webhook subscription (POST /v2/webhook)
    reversal: DELETE /v2/webhook/{id}
    window: none stated — deletable at any time
    grade: documented
  - action: list / contact / keyword / email-address / number configuration writes (v1 add-* operations)
    reversal: matching v1 remove/delete operations (remove-list.json, delete-from-list.json, delete-email.json,
      edit-number-options.json)
    window: none stated — deletable at any time
    grade: documented