Vertical alignment of \rbrace

Something like this?

\documentclass{article} 
\usepackage{amsmath} % for 'align' environment and '\text' macro
\newlength\mylen     % create a "length" variable
\settowidth\mylen{very long equation} % calculate default width of '\mybox'
\newcommand\mybox[2][\mylen]{\parbox{#1}{\raggedright #2}}

\begin{document}
\begin{align}
L = &\left.\mybox{short eq}\right\rbrace &&
     \text{description 1} \\
    &\left.\mybox{very long equation over multiple lines}\right\rbrace &&
     \text{description 2}
\end{align} 
\end{document}

How about something like this?

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\begin{equation}
\begin{alignedat}{4}
 L = & \text{short eq } && \left. \text{ }  \right\rbrace  && \qquad \text{description 1} \\
     &\begin{aligned}
         &\text{22244 very long equation 5555}\\
         &\text{over multiple lines }
      \end{aligned} && \left. 
      \begin{aligned}
           \text{ }\\
           \text{ }
      \end{aligned}  \right\rbrace && \qquad \text{description 2}
\end{alignedat}
\end{equation}

\end{document}

It looks like this

All the lines are treated as one equation. I borrowed the idea from the following post.

vertical alignment of multiline equations