short curly braces with tikz

Here is a primitive meta-decoration, but it is not as general as the standard brace such as raise,mirror etc. won't work. However, the brace amplitude and other local brace options are passed and would be available as I tried to show below. The new raise amount is controlled with meta-amplitude key.

\documentclass[tikz]{standalone}
\usetikzlibrary{decorations.pathreplacing}

\pgfdeclaremetadecoration{raisedbrace}{initial}{%
\state{initial}[width=\pgfmetadecoratedpathlength]{%
  \decoration{brace}%
  \pgfsetdecorationsegmenttransformation{%
      \pgftransformyshift{\pgfmetadecorationsegmentamplitude}%
  }
  \beforedecoration{
    \pgfpathmoveto{\pgfpointmetadecoratedpathfirst}
    \pgfpathlineto{\pgfpointadd{%
      \pgfpointmetadecoratedpathfirst%
      }{%
      \pgfpointpolar{\pgfdecoratedangle+90}{\pgfmetadecorationsegmentamplitude}%
      }%
    }%
  }%
  \afterdecoration{%
    \pgfpathlineto{\pgfpointmetadecoratedpathlast}%
    \pgfusepath{stroke}
  }
}
}
\begin{document}
\begin{tikzpicture}
\draw[style=help lines] (-1,-1) grid[step=1cm] (3,3);
\draw[decorate,decoration={raisedbrace,amplitude=2mm,meta-amplitude=4mm}]  (0,1) -- (2,2);  
\draw[decorate,decoration={raisedbrace,amplitude=4mm,meta-amplitude=1cm}]  (0,-1) -- (2,-0.5);
\draw[decorate,decoration={raisedbrace,amplitude=1cm,meta-amplitude=5mm}]  (2,3) -- (2,-0.5);
\end{tikzpicture}
\end{document}

This should help you:

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing}

\begin{document}
\begin{tikzpicture}[scale=1]
\draw [decorate,decoration={brace,amplitude=10pt},xshift=-4pt,yshift=0pt]
(0.5,0.5) -- (5.0,0.5) node [black,midway,xshift=-0.6cm]
{};
\node at (2.65,1.0) {text};
\end{tikzpicture}
\end{document} 

The length of the brace can be altered with the values in the \draw command (0.5,0.5) -- (5.0,0.5). Similarly the text position need to be altered.

Update

Varying the amplitude, we get something like this:

Code

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing}

\begin{document}
\begin{tikzpicture}[scale=1]
\draw [decorate,decoration={brace,amplitude=14pt},xshift=-4pt,yshift=0pt]
(0.5,0.5) -- (5.0,0.5) node [black,midway,xshift=-0.6cm]
{};
\node at (2.65,1.2) {text};
\end{tikzpicture}
\end{document}