Comment by evanelias

"Declarative" is the correct word, as the input to the tool is a desired-state set of CREATE statements, and the tool figures out what DDL is actually necessary to make the target DB reach that desired state.

In other words, the engineer is declaring "make my schema look like this" and the tool makes that happen. That's the key definition of a declarative system, consistent with how this is described in CS classes.

Meanwhile traditional migration tools are "imperative", as the engineer must tell the tool exactly what operations (e.g. ALTER) to be run.