SendMessageTool
Sends an SMS to to with text body via SmsManager (version-checked: system service on API 31+, else getDefault()). The recipient must match phoneRegex or an error is returned; bodies over 160 chars are split with divideMessage/sendMultipartTextMessage. Requires SEND_SMS. Output on success: sent (true), echoed to, and body_length; failures return an error with the exception message.