We have gone in August for a few years now. If you can go any other cooler time, then go then

But if you can't, then that's when you can go.
Get out early every morning. The heat becomes absolutely brutal in the afternoons. Get your must-dos done in the mornings as well. There are daily storms with lightning usually in the afternoons. Sometimes the swim-in-the-afternoon strategy can be tricky but if you wait it out, you can usually find a time to do it.
We like to have an in-park lunch ADR around 11 am and then we usually do QS for dinner at the resort or wherever. We find that the sit-down break refreshes us to keep going.
Make your touring plans with AC attractions built into it (those nice ones where you can sit for a bit and cool off

).
Some parks are worse than others. World Showcase is the hottest place on earth during the day in the summer. FutureWorld isn't as bad because lots of big buildings. Hollywood Studios is relatively decent too. MK is surprisingly not as bad because there are so many places to go in and out of. We often skip AK entirely in August.
The crowds decrease as the month goes on, as do the prices. On the flip side, compared to the cooler months, you can't get as much done in a day usually, so it's a tradeoff there.
Anyway, an August trip can be great, if you go into it with the right expectations.