Fastest/minimum git operation to check if a tag exists and what branch it's in -

i working in opscode repo, , need information bunch of other repositories. when issues "deploy" command, may provide branch or tag (or possibly other refspec) deploy to. example…

deploy main_app==1.2.3 deploy main_app workflow_app==4.5.6 deploy app_config==ugly-test-branch 

main_app, workflow_app , app_config in different repos, , none in repo i'm in.

for each repo, want determine if given refspec exists, , if not branch, branch in?

i can answer first question git ls-remote, there way tell branch object in without @ least doing git clone --bare?

if want history structure you'll have fetch history or talk server has access it. there's number of show-me-the-repo-structure servers out there, built-in git instaweb github, rely on having actual repo handy can show what's in it.