Amir Garrett should be on the Astros radar.
There's a reason the word "trade" was left out of the headline. Most moves the Astros make will be a trade, but the veteran reliever was recently released outright by the Kansas City Royals.
On paper, his 3.33 ERA looks like Garrett would be a no-brainer, but his walk-rate is remarkably high. He walked a career high 7.4 per nine before being DFA'd by Kansas City. With his troublesome control, he'd likely slide into a similar role as Ryne Stanek last year. Walks don't play in October, so while he likely wouldn't be trusted to get leverage outs then, he could be great depth for the bullpen now.
Even if his walk rate didn't improve, he's still a better option than Joel Kuhnel. A flier on Garrett wouldn't cost any prospects from an already depleted farm system if they looked to make other moves, and if he regained form throwing for a team actually going somewhere again, he'd be a tremendous asset for the bullpen.
Worst case, he provides needed depth to keep innings down and the lefty Dusty Baker so desires. Best case, he actually can be counted on for leverage outs throughout the regular season. This is a low risk, high reward move the Astros should make.