An MCP server is the program on the other end of an MCP connection: the one that has something to offer. Despite the name, it does not have to run in a data center. It can be a small program on your own laptop, reachable over a local connection instead of the internet.
Birta runs one for publishing. It advertises tools such as listing your projects, uploading a build, and rolling back a version, and your connected agent calls them directly instead of you clicking through a dashboard.
For how a server relates to the host and client around it, see what MCP is and why it matters for publishing.