Twilio

Twilio API Skill

Overview

Twilio provides programmable communication tools. This skill details the SMS and Voice APIs, emphasizing webhooks for incoming messages and TwiML for call routing.

Installation

npm install twilio
pip install twilio

Authentication

Authenticate using Account SID and Auth Token. Keep these strictly server-side.

Core Concepts

• TwiML: XML-based language that instructs Twilio on how to handle calls and SMS.
• Message SID: Unique identifier for tracking message delivery status.

Common Workflows

1. Instantiate Twilio client.
2. Call messages.create with to, from, and body.
3. Poll or use status webhooks to confirm delivery.

Error Handling

Handle the TwilioRestException. Code 21211 means 'Invalid 'To' Phone Number'. Handle gracefully in the UI.

Security

Validate incoming webhooks using twilio.validateRequest to ensure requests actually originated from Twilio.

Rate Limits

Standard SMS throughput is 1 message per second per long code. Toll-free and short codes have higher limits.

Best Practices

Use Messaging Services instead of hardcoded numbers to automatically handle compliance, opt-outs, and sender ID rotation.

Troubleshooting

If international SMS fails, check your Geo-Permissions in the Twilio Console.

References

• API Reference

Why use this skill

Use this when your agent works with twilio — structured patterns beat pasted docs and prevent common hallucinations.

AI pitfalls

• Using outdated SDK or API versions from training data
• Inventing environment variable names
• Omitting error handling and retry logic

Production checklist

• Secrets in environment variables, not source code
• Error handling and logging in place
• Rate limits and timeouts configured

Related skills

• sendgrid — related to

Last Verified: 2026-07-02