Formula Dog barely does what it claims. Its answers are minimal, lacking context, can't be modified, and are occasionally wrong. In order to keep this, the tool would have to give me some sort of advantage over just going to ChatGPT and asking that AI directly. It doesn't.

I tested it with the both the creation of spreadsheet formulas and explaining existing formulas. I also had it explain Regex code.

I started with a complex Google Sheets formula that I wanted it to build. I described to ChatGPT what the formula needed to do. It gave me the formula along with explanation of what the various parts do.

I decided that I wanted to refine the formula, so I told ChatGPT "Please modify the formula in cell F2 to display a number if numeric values exist in all of cells B2 through E2, but display the word "ERROR" if any of cells B2 through E2 are blank or contain non-numeric values." I was able to do several rounds of this until I got what I wanted. ChatGPT retained knowledge of my original query and modified the formula based on my later changes. The answers it gave were always correct and had a lot of additional explanation and context.

I then fed the final version of my query into Formula Dog. Formula Dog gave me the correct formula, but there was no explanation or context.

I also fed FD my orignal ChatGPT prompt. After FD gave me the answer, I tried to refine the formula as I had with ChatGPT. I told it "Please modify the formula in cell F2 to…[etc.]". Unfortunately, FD has no memory of what you did before. Formula Dog just GUESSED about what I was talking about. It correctly got the part of the formula related to what I had mentioned in the most-recent prompt, but the rest of the formula was missing. This is a clear failure.

Next I tried having the AIs explain the Google Sheets formula (try it yourself!):
=IF(AND(ISNUMBER(B2), ISNUMBER(C2), ISNUMBER(D2), ISNUMBER(E2)), (E2*D2)-(B2+C2*D2), "ERROR")

ChatGPT thoroughly explained the formula. It even broke out the second formula in there and explained that one by itself. Formula Dog just gave me a terse (but correct) answer. If I were having trouble trying to understand a complex spreadsheet, the ChatGPT answer is way more helpful.

Finally, I had the AIs explain this regex code (try it yourself!):
.?(\\d{3}).*(\\d{3}).*(\\d{4})

ChatGPT's answer was correct and thoroughly explained. Formula Dog gave a typically sparse answer that was incorrect in two ways.

ChatGPT said:
"The initial . and ? together match an optional single character at the beginning of the string."
Formula Dog didn't even mention that string, let alone tell me that it was optional.

ChatGPT also said:
".*: Matches zero or more occurrences of any character except a newline."
Formula Dog said:
"followed by any number of characters"
This does not specify that "any number" could be zero. It also doesn't mention the newline.

I'm going to hang onto this for seven weeks to see if it gets a lot better. If not, I'm refunding.