Title and meta description is important for any page. For example if I take a forum website, the title will be the same as the question asked.
What about the description? Should I leave it blank or should I make it same as the title name?
You have to know what is the difference between not including meta description and writing your own.
If you don't include meta description in your code Google and other search engines will take first 150-160 characters of the page, navigations and tabs shouldn't be included in this 150-160 characters but, it is definitely not a good idea to let search engines choose what do display.
If you are going for a CMS solution your best approach is to go for excerpt in main lanes it will do the same thing as mentioned above, it will take first
X count of characters depending on the setting, but it will take it only from the post content and not from the whole page, so you won't have to be worried about usernames, age, cities, breadcrumbs, etc..
I might be missing something.
Short Answer - If you're using forum, then don't waste your time on it.
There are too many myths about meta description, for example, Google will display your meta description as you have written, so you will get better CTR from search result, But most of webmaster forgot this Google simply ignore your meta description as per user query. And most of time, user query is not matched with your meta description.
For example, this is my meta description for one of my webpage
"Step by step tutorial to understand, how Google treat your meta description and let's closely look out on some myths about meta description"
And let's assume I have write this line in body content,
"The maximum character limit of meta description is 160"
Now, if user type in search
Tutorial about meta description, then you might get your desire meta description in SERP.
But, if user type in search
Maximum Character limit of Meta Description then Google will automatically generate meta description for user and it contains some words which is related to user query and it will highlight into SERP.
And ask your self, have you read all search snippet that display in Google search result?, Most of people look out on just heading line, and some of texts which is highligh in SERP. No body will going to read your whole meta description.
So don't focus on meta description, lot's of times it simply ignore by Google. You can use any functionality to truncate your first paragraph automatically and use it as meta description. Google itself, generate meta description automatically, look out any of article from support.google.com
Forums that work like a Q&A should use the first characters in the question text. Because lots of people will arrive to the page because they have similar questions.