What are the key points in short descriptions of research experience?
In a one-sentence statement, I want to state as precisely and concisely as possible as much relevant detail about the project I was working on. For instance 


  Analysis of Widget Manufacturing


doesn't tell me much about what you did. On the other hand


  In-situ XYZ Experiments and Numerical Modeling of the Parametric Influence of Temperature, Humidity, and Cooling Time on the Strength of Widget X under Load-Bearing Conditions


tells me much more about the problem you're working on.

If you have perhaps a paragraph, then I went a short summary of your work. You should provide: a motivation for the problem, an overview of what you did, and a summary of the main methods, results, and conclusions of the work.