This is an alternative to Ansible, which is an agentless system administration tool.
You define a set of tasks, explain how they should run and on which servers, and run on a potentially large set of computers via SSH. Nothing is installed on the remote nodes you are targeting.
A typical scenario would be "install php on web servers, fill this nginx configuration template then push it to /etc/nginx/site-available/, make a link from /etc/nginx/sites-enabled, on database servers only install PostgreSQL, etc. etc."
I think this tool is promising, as ansible is quite slow and error-prone. But with software alternatives there's always the problem of feature coverage and community adoptions and support.
But it's a bit of a chicken-and-egg problem. Without users, I don't know how it should be used, without features I won't get any users. So for now, it's in a state of "I'll address bug reports and feature requests, but I won't actively develop it".
I guess in Rust it wouldn't take much work to add support for YAML and keep the checks.
Also note that Ansible is slow with default ssh arguments. When configured properly it's quite fast!