Domain tools

The greatest tool would be wisdom, which you can gain from reading and experience

There are many but I would start with

NameBio to research what similar domains have sold for

Dofo to research which extensions are registered and for sale

Google for many things

TLDlist or DomComp to get best pricing on transfers and renewals

The automated like GoValue, Estibot, NameWorth just to see range of automated valuations and GoValue to get many comparator sales not in NameBio

NamePros daily to learn many things about many topics!

Best wishes for success in domain investing, @Mrkool and welcome to NamePros!

Bob

I would give another vote for namebio, to give you instant access to search for how much domains sold for, using the filters to narrow down your results too.

The tools are there, but it is how we use them to extract data.

There are tools to help analyse keyword popularity many domainers here read this totally wrong quoting single word stats on their two word domains and makes their domain advertisement a complete lie.
There is no one (robot) tool to tell you whether a human will buy it. Use the cpm and keyword data supplied to make assessments.

GoDaddy auction is the best place to start..