perforce action label command fails with "buffer not large enough"

[epu]

perforce action label command asserts "Buffer not large enough." and fails when I have a large Descr: field in the Client Spec/Label tab of the step properties window. The Descr: field is a handful of macros that expand to much larger text. The yellow pop-up tool-tip window for the Descr: field text ends with an ellipses"..."; the complete contents are not displayed.