No.

This would be a meta tag and the consensus around StackExchange is they are generally a bad thing.

A few more reasons why this is a bad idea:

• There are sometimes too many caveats that need to be explained to say if the question is confirmed or not. For example the worm question.
• Answers are generally encouraged to have a tl;dr at the top anyway, which is more flexible, especially when the answer is "yes... but"
• The way the question is worded would change the tag. For example compare "Does astrology work?" (No) to "Is astrology a pseudo-science?" (Yes). So I am not sure it will provide anything meaningful outside of the question/answer itself.

No.

This would be a meta tag and the consensus around StackExchange is they are generally a bad thing.

A few more reasons why this is a bad idea:

• There are sometimes too many caveats that need to be explained to say if the question is confirmed or not. For example the worm question.
• Answers are generally encouraged to have a tl;dr at the top anyway, which is more flexible, especially when the answer is "yes... but"
• The way the question is worded would change the tag. For example compare "Does astrology work?" (No) to "Is astrology a pseudo-science?" (Yes). So I am not sure it will provide anything meaningful outside of the question/answer itself.