What information do you wish clients included when reporting a bug?

One of the biggest problems we noticed while working on client websites is that a bug report often looks like:

“The button isn't working.”

Then comes the inevitable:

“Which page?”
“Which button?”
“Can you send a screenshot?”
“Which browser are you using?”

That problem is what led us to build BetaSpotter.

Instead of asking clients to explain everything, they can click directly on the website and report the issue with the relevant context captured automatically.

I'm curious — what information do you wish clients would include when reporting bugs or requesting changes?