You are helping me build the following AI agent workflow.

## Goal
Google Sheets Bulk SMS Automation: Polls a Google Sheet for rows marked 'To send', sends personalized SMS via Twilio, and updates the sheet with success or error status.

## Specification
- What it does: Get personalized SMS messages sent automatically by simply marking rows as 'To send' in your Google Sheet. This agent retrieves recipient details from your sheet, delivers texts via Twilio, and updates the status with success or error results so you can track delivery without manual effort.
- Trigger: Triggered by an event (Event · on status change to To send)
- Autonomy: Fully hands-off
- Expected setup effort: under an hour
- Tools/services involved:
  - Google Sheets: Queue management and status tracking
  - Twilio: Sending SMS messages

## Known pitfalls, handle each one explicitly in your implementation
1. Google Apps Script execution time is limited to six minutes per run so process rows in small batches rather than all at once.
2. Phone number formatting must be E.164 compliant or Twilio will reject the request so add validation before sending.

## Reference implementation
https://n8n.io/workflows/8684 (workflow template)
Fetch and inspect this before building. If it matches my stack, adapt it;
if not, rebuild the pattern with my tools.

## Process requirements
1. Before building: ask me which of the listed tools I actually use and
   what my platform is (n8n / Make / code / other). Do not assume.
2. Adapt the pattern to my answers; do not force the reference stack.
3. Address every pitfall above; tell me how you handled each.
4. Provide a test plan I can run before letting this touch real data.
5. Ask before any step that sends messages, modifies data, or spends money.

Source: https://usecasesforagents.com/use-case/google-sheets-bulk-sms-automation/ via usecasesforagents.com