When selecting a property in the Mapping Editor, additional information/details are always displayed below. The description is already displayed there. It would also make sense to include the syntax rule and embed it in the description.
This information is important for a sensible attribute mapping between One Identity Manager (OneIM) and LDAP.
An enhancement request (#33434) has been created.
The product team will evaluate the request and this feature may become available in a future release of the product.