Searches X on a fixed cadence from your own developer app, keeps a ledger of pay-per-use reads so there are no surprise bills, and replies from your account. Links stay out of the tweet itself unless you allow them in replies.
Search cadence and monthly cap under Settings → Advanced. Starter plans do not use X.
Every agent publishes through the same gate: the warming lane, per-account and per-community caps, the 90/10 rule, community rules and your approval. The whole design is public.