Change tooltip for custom field (ex. Text1) in MS Project

Question

Is there any programmatic way to change the tooltip for a custom field (Text1-30) through VBA (or by hand)?

When I rename a custom field, it displays the new name at the top of the field, but the tooltip when you hover over the header is still generic like:

MyNewFieldName (Flag1)

A custom field you can use to indicate whether a task, resource, or assignment is marked for further action or identification of some kind.

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