The cartoon was intended to be an exercise in silliness. While I have never met a cow who could make tools, I felt sure that if I did, they (the tools) would lack something in sophistication and resemble the sorry specimens shown in this cartoon. I regret that my fondness for cows, combined with an overactive imagination, may have carried me beyond what is comprehensible to the average Far Side reader.
The ultimate punchline that Mr. Larson was aiming for is that cows don't get it. The result is a bunch of readers who also don't get it. It's really funny in an ironic way.
I may be misremembering, but I believe there is another quote of his about how he regrets making one of the tools look like a saw. He wanted all of them to be totally nonsensical items.
finally we no longer need to analyze this and wonder what we're missing. It requires no analysis. Cow tools. That's all. Well done, Gary Larson. This one became iconic for its bland nothingness.