The spec text currently reads:

If a document contains only one operation and that operation is a query which
defines no variables and contains no directives then that operation may be
represented in a short-hand form which omits the {query} keyword and operation
name.

The word "contains" here is ambiguous, and it makes it sound like the following query is invalid since it "contains" a directive:

{
  __typename @skip(if: true)
}

Really we mean that there is no direcive applied to the operation itself (directly); I've attempted to clarify this without making the text more verbose.