\begin{equation*}\begin{tikzpicture}[description/.style={fill=white,inner sep=2pt}]
    \matrix (m) [matrix of math nodes, row sep=3em,
                 column sep=2.5em, text height=1.5ex, text depth=0.25ex,
                 inner sep=0pt, nodes={inner xsep=0.3333em, inner ysep=0.3333em}]
    {

    };
    \path[->,font=\scriptsize]
    % (m-x-y) edge node[auto] {beschriftung} (m-xp,yp)
\end{tikzpicture}\end{equation*}