Everyone is shipping an "AI SDR" right now. Most of them are spam cannons with a fresh coat of paint.
1. It researches before it writes
A great SDR agent reads the prospect's site, recent news, and role before composing a single line.
2. It writes like a person
Short. Specific. No "I hope this email finds you well."
3. It knows when to stop
The best agents recognize a hot reply and hand off to a human immediately, with full context attached.