VHDL-Tool makes its services available to Atom through the Language Server Protocol.

Atom plugin

$ git clone https://git.vhdltool.com/vhdl-tool/vhdltool-atom 
$ cd vhdltool-atom
$ apm install
$ apm install language-vhdl
$ apm install nuclide

Then launch Atom from the root of your design, where the configuration file is located:

$ atom .


Make sure vhdl-tool is configured properly by running vhdl-tool check-config in the directory containing the configuration file.