When a function object is given to describe function documentation is not shown (it's shown on the symbol). Because of this, the slime function documentation doesn't show it either.
Index: src/org/armedbear/lisp/describe.lisp =================================================================== --- src/org/armedbear/lisp/describe.lisp (revision 14850) +++ src/org/armedbear/lisp/describe.lisp (working copy) @@ -89,7 +89,13 @@ (setf plist (cddr plist)))))) (FUNCTION (%describe-object object stream) - (describe-arglist object stream)) + (describe-arglist object stream) + (let ((function-symbol (nth-value 2 (function-lambda-expression object)))) + (when function-symbol + (let ((doc (documentation function-symbol 'function))) + (when doc + (format stream "Function documentation:~% ~A~%" doc))) + ))) (INTEGER (%describe-object object stream) (format stream "~D.~%~