curl --request POST \
  --url http://localhost:3000/api/openapi/agent/messages/send \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "threadId": "<string>",
  "message": "<unknown>",
  "attachmentIds": [
    "<string>"
  ]
}
'

"<unknown>"