No, this is status-bydesign.
Actually, /tags page is looking for excerpt, while /tag/tagname is looking for wiki summary.
If you take a look at the other tags, for example c#, you'll see that in /tags it's
a high level, general-purpose object-oriented programming language created by Microsoft.
in /questions/tagged/c#, it's different, too
C# is a multi-paradigm, managed, object-oriented programming language created by Microsoft in conjunction with the .NET platform. C# is also used with non-Microsoft implementations (most notably, Mono). Versions 1.0/1.2 and 2.0 of C# were submitted and approved as both ECMA and ISO/IEC standards. ...
Take a look here and I think you'll get what am I talking about