Can we add formula (tool) in brew list? According to brew document(https://docs.brew.sh/Manpage) we can install tools which Apple didn’t include with macOS.
Can we add our custom (third party) tool in brew list (https://formulae.brew.sh/formula/) and if yes then what is procedure for it.
The rules limit what is an acceptable formula so having your own tool accepted would seem to depend on its popularity.


  Niche (or self-submitted) stuff
  
  The software in question must:
  
  
  be maintained (i.e. the last release wasn’t ages ago, it works
  without patching on all supported macOS releases and has no
  outstanding, unpatched security vulnerabilities)
  be known
  be stable (e.g. not declared “unstable” or “beta” by upstream)
  be used
  have a homepage
  
  
  We will reject formulae that seem too obscure, partly because they won’t get maintained and partly because we have to draw the line somewhere.
  
  We frown on authors submitting their own work unless it is very popular.


You can however create your own tap containing whatever you want. See How to create and maintain a tap 


  Taps are external sources of Homebrew formulae and/or external commands. They can be created by anyone to provide their own formulae and/or external commands to any Homebrew user.