How do you usually choose a digital agency when you need several things at once, like a website, SEO and some custom software? I am curious what people here look at first before the budget talk even starts.

I have been comparing a few full service agencies because splitting web development, SEO and design between separate contractors turned into a mess for us. The first thing I try to check is how clearly each direction is described and whether the scope is defined before any payment. One agency page I looked at listed custom software, website development and SEO as separate services with their own descriptions, and if you want to view that kind of structure it becomes easier to compare against others. What I still cannot judge is whether a quote for a mixed project is reasonable or simply inflated by bundling everything together. For now I am keeping two or three options and reading the terms carefully.