Agent send_sms tool

Bind the send_sms builtin to an agent with a fixed fromPhoneNumberId. The model only supplies to and text; it cannot choose a different sender or spoof a campaign.

{
  "name": "send_confirmation_text",
  "description": "Send the customer the confirmation they requested.",
  "parameters": {
    "type": "object",
    "required": ["to", "text"],
    "properties": {
      "to": { "type": "string" },
      "text": { "type": "string", "maxLength": 1600 }
    }
  },
  "executionMode": "builtin",
  "source": {
    "kind": "builtin",
    "name": "send_sms",
    "config": { "fromPhoneNumberId": "8f0e9a96-..." }
  }
}

At execution Speko verifies that the bound number belongs to the same workspace and agent, then applies the same readiness, consent, suppression, quiet-hour, idempotency, and credit-reservation pipeline as the public API. The tool returns the durable message ID and current status. It never claims immediate delivery.

Inbound auto-replies use the same central send service and incur both the existing LLM charge and SMS segment charge. They remain off until explicitly enabled on the organization, number, and conversation.