I hope that is not too late for an answer. We develop ReqView (reqview.com) software and system requirements management tool. I believe that the FREE plan suits most of your needs.
With the FREE plan, you can open any ReqView project as read-only, browse requirements, traceability links, sort, filter and print requirement views. The FREE plan limits size of ...
Your company's working methodology (non-waterfall) suggests that a wiki would be the best tool for that.
First, you will need to import your existing specification into the wiki.
Then at each evolution you will edit the relevant pages to add/remove/modify functional descriptions and requirements.
Efficiently keep the specification up-to-date (wiki ...
ReqView might meet your needs.
It must be simple enough
and it's advertised as
Ease of Use
Capture well structured requirements in a familiar tabular view
resembling MS Word and Excel.
and indeed, it has a common editor:
Since you can leave the text empty, it also fulfills
start with no mandatory properties except a title
Trello seems to be simple enough for my needs. Can create columns and creating items in each column is fast and easy. Projects are hosted on online account and as such accessible from anywhere (web portal + android app). It's free too.
I don't yet know if it'll satisfy my 4, 5, 6 requirements need to work with it a bit.
I know of pyqver and used it sometimes but it seems it's been years with no developed/updates, so it could still be useful if you're dealing with old scripts but if you have to check code that requires one of the most recent Python ( > 3.3 ) version you can't rely on it... I don't know if there are newer tools for that purpose.
Unfortunately I can not speak for MS TFS nor IBM. But I have a strong experience with many Atlassian tools, as a user and as an administrator. With Jira, I have even written a few plugins (synchro tasks, custom gadgets, ui override etc.)
What I can tell: don't hesitate. It's worth the cost. It's great piece of software. It can be a bit hard to get the ...