What is a closed design brief?
A closed design brief
This will limit the range of solutions you can determine for your project and narrow the likely outcome by suggesting the type of solution you have to produce. It doesn't tell you exactly what your design will look like but it will state what the solution will be.
Are design patterns hard?
The main problem with design patterns is that they are not necessarily easy to learn. Many developers, especially the ones who don't have a lot of software-building experience, struggle with them.