Apple today released Server Admin Tools 10.5.6v1.1 which contains remote administration tools, documentation, and utilities that you can install on a computer other than your server.
This version is required to administer Mac OS X Server version 10.5.6 from a remote Mac client. The Server Admin Tools 10.5.6 are available as a manual download from Apple Support Downloads, and as an automatic Software Update for Macs running Mac OS X 10.5.6 with version 10.5 or later of the Server Admin Tools already installed. Note: The Server Admin Tools 10.5.6 require Mac OS X version 10.5.6.
More info and download link (92.7MB) here.