Q:

Tag length limit may be limiting technology discoverability

I was editing a question's tags this morning and ran into the tag length limit:

I understand the rationale for this to be that there needs to be some reasonable length of tag names, but this example has me questioning if 25 is the right length. Here's why:

Tags have the following properties:

They are searchable on Stack Overflow.
Because tags are searchable, they associate questions with similar questions.
Can lead users to find the right answers. For example, if a similar question has a tag pointing to a technology that an OP wasn't aware of.

Objective-C traditionally has verbose class names and even more verbose method signatures. 
Class names seem to be valid tags. (This meta request makes a similar assumption.)

In this particular case, I wanted to add the tag to the question so that the OP and other users know to use UITableViewHeaderFooterView instead of UITableViewCell inside the framework method that the OP asked about. I can tag the question UITableViewCell, but that was the exact mistake the user was making, expressed as a tag. (Using one class instead of the other.)
I said as much in the answer, but the absence of the tag is obscuring the existence of the technology in some way and a missed opportunity for tags.
As such, we probably want to allow users to be able to tag questions with the "technologies" being used. This begs the question: how granular should tags be?
Given this understanding of tags, should we have a longer maximum tag length? Should tags be less specific if the class name is longer than the max length?

A:

There is a practical limit to how specific tags ought to be.
The principal purpose of tags is to make it easier for answerers to find questions to answer. I'm not an Objective-C user, but if I were looking to answer questions about Objective-C APIs, I'd probably look in the Objective-C tag, or the iOS tag or whatever. I would not be looking for questions about every class in Objective-C's API.

In this particular case, I wanted to add the tag to the question so that the OP and other users know to use UITableViewHeaderFooterView instead of UITableViewCell inside the framework method that the OP asked about.

Even if we ignore the above, this is still wrong. Tags are for the question, not the answers. You don't tag questions based on how you solve the problem; you tag questions based on what the problem actually is.
That is how we let people know what technology to use. You see someone ask about X, and you read the answer showing how to use Y to do that job.

