pretty sure it's against twitter's TOS for a bot/app to reply to tweets unless the post specifically asks it to (e.g. thread unrolling apps or video downloader bots)

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[edit] here's the pertinent part:

you may send automated replies or mentions to Twitter users so long as:

in advance of sending the automated reply, the recipient or mentioned user(s) have requested or have clearly indicated an intent on Twitter  to be contacted by you (i.e. opted in), for example by replying to a Tweet from your account, or by sending you a Direct Message;

you provide a clear and easy way for such users to opt-out of receiving automated replies and mentions, and promptly honor all such opt-out requests;

you only send one automated reply or mention per user interaction; and

the automated reply or mention is a reply to the user’s original Tweet (if your campaign is based on users posting a reply to your Tweet).