So I guess everybody knows about the MCA Troubleshooter by now. I'm not going to talk about that one as I think he'll take a dive once the agent from the Errata Corporation in Minnesota gets his ass to Mars.
I have to say, I kinda like MCA Informant. It's not a strong card but it's nice from a game design perspective. The idea behind MCA Informant is to make one of the runner's connections a snitch and make the runner pay up or risk corp retaliation through a tag. This forces a choice on the runner and forcing choices on your opponent should increase the interactivity and tension of the game, both good things.
Because MCA Informant only works on connections there's a limited list of options. Looking through that list we have some familiar names like Professional Contacts, Street Peddler, Film Critic, Tech Trader, Political Operative, Technical Writer, Beth Kilrain-Chang and Aaron Marrón.
However not all of these are suited to put MCA Informant on. Cards that trash themselves kinda defeat the purpose of forcing a choice, the runner will simply trash them. That means Street Peddler and Technical Writer aren't good choices.
Another way to get rid of MCA Informant is by simply installing a second version of a unique card. Most connections are unique. This is a good way to replace that snitch Aaron Marrón with it's own twin brother (I guess he learned that trick from Rene at the cafe).
A third way is to consider The Price of Freedom. Ok, it's a bit silly but if MCA Informant ever becomes popular it's a good counterplay. I do think The Price of Freedom deserves a special ruling that you can pay with corp cards with it though.
Assuming you've got MCA Informant installed, is it any good? Well... kinda. Most of the time the runner will simply trash the connection, most aren't that critical and being tagged is generally worse. So it's probably click 1: pay 2 and dump the snitch. It's a bit of a tax but it's not very reliable since you don't know if the runner will have use connections.
Most useful is probably rezzing a Zealous Judge. If it's well protected enough that gives you the option of tagging the runner at the start of your next turn so you can unless corp payback.
A more creative option is scoring a sufficiently advanced Market Research. It's not terribly easy to do but if you can get the combo off that's a 4/3 you scored and one that's only a 4/2 to the runner.
In Harishchandra Ent.: Where You're the Star even having the runner tagged for a little while gives you valuable information.
That's about all I can think of though. I'm sure someone will pop up in the comments to point out the obvious thing I missed because my palm hasn't has sufficiently close contact with my forehead today yet.
MCA Informant is an interesting card and I hope FFG will explore this part of the design space further, but as is (without the Corporate Troubleshooter accidental combo) it's not really a strong card. I wouldn't want to call it very weak either however, it's applicable in enough cases that there's a fair chance you'll get some value out of it.