In this long post, I will describe a few issues associated with tags that I believe should be solved. Feel free to add your opinions regarding the issues or specific tags (or feel free to edit this question to add more issues or tags)
Tags that should NOT exist
I've observed that, on this website, there are a lot of tags whose meaning is not widely accepted yet or it is not understandable. For example, unassisted-learning. I've never heard of this expression before (and I am involved in the field of AI). Even though an expression occurs in a web article, it doesn't mean that it deserves a tag on this website.
I believe that only topics that have a "considerable amount" of associated research literature should have an associated tag, for example, questions related to ant colony optimisation (ant-colony) or related to on-policy or off-policy RL algorithms.
There are other tags that I believe should not exist on this website:
bayes should not exist because there are more meaningful tags (with respect to AI), such as bayes-theorem (which already exists); maybe we could also have the tag probabilistic-graphical-model (which includes e.g. Bayesian networks, whose tag bayesian-network already exists) for some questions that are currently a little bit ambiguously tagged with bayes); some of the questions that are currently tagged with bayes can instead be tagged with naive-bayes (which already exists).language-processing should be deleted because there is already nlp or natural-language-processingai-community(why exactly do we need this tag? what the relation between this tag and social? Do we need both of these tags, anyway? what's the relation between ai-community andtheory?)software-architecture (similarly to software-evaluation)self-driving ("self-driving" this an adjective; the tag autonomous-vehicles is a synonym for self-driving, but I would completely delete self-driving)cars (similarly to self-driving, this tag should be deleted)world-knowledge should be deleted because there is already knowledge-representationreal-worldshould not exist, given that there is already the tag applications, which should cover all types of applications, so this tag should be deleteddetecting-patterns should not exist because there is already the more common expression pattern-recognition; it should not even be considered a synonymprobabilistic should not exist because it an adjective and it not widely used; the non-existing tags probabilistic-model or statistical-model would have been better; anyway, the tags math or statistical-ai should somehow already cover associated questions, so I suggest to delete probabilistic(temporarily solved by renaming it to probability).predicting-ai-milestones (there are already the tags prediction; maybe we should have the tag ai-milestones, but I think that the tag history already covers this)ai-methods (theory should cover this)quotes (maybe this could exist as a sub-category of history)theorics currently points to theory, but can't we simply delete it?ultraintelligent-machine (there is already superintelligence, and ultraintelligent-machine is, AFAIK, not very common; a more common expression would be universal-intelligence, but I would just have superintelligence)deepqa, similarly, currently points to watson, but can't we simply delete it?
brain maybe should not exist because there is already biology, which should include all questions related to biological inspired AI, but maybe we can also keep it (given that the brain is an important inspiration)
challenges (there are challenges everywhere; this tag is very vague)[removed this tag from all posts, as it's very ambiguous and was being used inconsistently]embedded-design (maybe this tag should not exist)
structured-data (I have no idea why this tag should exist)
topology (How is this tag different from architecture? Maybe this should at least be clarified)
software-evaluation (this has nothing to do directly with AI; this tag should really not exist on this website, IMHO)
In general, as a rule of thumb, if a topic or expression does not have an associated Wikipedia article, it likely means that a corresponding tag should not exist on this website. I have not given a motivation for each of the tags, because otherwise I would not do anything more today. It is possible that in some cases I am not seeing the reason of the existence of the corresponding tags. However, I believe that most of them should not exist.
Duplicates
There are tags that are duplicates
theoryandconcepts(I would leave just first one, given that the first tag is more "standard", even though we can have synonymous tags)comparison and relation (I would say that they can co-exist on this website)strong-ai and agi are essentially synonymous and they can both co-exist (given that both expressions are common)
It is possible there are a lot more duplicate tags.
Tags that need improvement
There are tags whose definition is not clear or inconsistent with the existing posts on this website. For example, the tag chat-bots, whose current definition states
For questions about chat-bots. NOT for questions about how to program a chat-bot, as those kinds of questions are off-topic.
However, one of the highest upvoted question on this website with this tag is https://ai.stackexchange.com/q/3343/2444.
Other tags that possibly needs improvement are biology and brain. In their current description, they have no relation to AI (so they should not even exist). These tags could be used for questions that are both related to biology (and the brain) and AI at the same time (e.g. human-inspired AI, whose tag, btw, already exists on this website).
I suspect that there are a lot more tags that need an improvement, in terms of description and scope.