While Retool's interface suggests that we can make use of any dynamic values inside of the Input description (see first screenshot below), it turns out this doesn't actually work in practice. Please refer to the second screenshot, where you'll find the variable not rendered as expected.
P.s. You might ask why you would want to use dynamic values for this field. Well, it would allow for very helpful autocompletion based on certain data. In other words, I would be able to provide highly specific details regarding the intended purpose and context, without having to hard-code this.