Book or StackOverflow: this isn't a "tool," and the developer is expected to have sufficient skill to evaluate the information provided. If they can't do this then they're not qualified for that project.

A keyboard would be an example of a source whose output is 100% verified: we assume that you can see what you're typing. A process with 100% verification does not need to be separately qualified or validated.

I'm not sure how monitor errors could factor into this, can you elaborate?