Use #ID to link to work items
VSTS | TFS 2018 | TFS 2017 | TFS 2015.1
Feature availability: The #ID special control is supported from VSTS and TFS 2015.1 and later versions.
Link a pull request to a work item
When leaving a code comment in a pull request, you can type # to trigger the #ID work item picker. The picker displays a list of 50 work items that you have recently modified or that are assigned to you.
You can narrow the list of suggested work items by entering keywords that match the work item type, ID, or title, or you can enter the exact work item ID.
To further filter the list, continue entering keywords until you've found a match. You can enter up to five keywords.
Link to work items in pull requests, comments, and commits
Feature availability: The #ID special control has been extended to additional objects when working from VSTS and TFS 2015.2 and later versions.
You can also use the #ID control in pull request discussions, commit comments, changeset comments, and shelveset comments.
Link to work items from a Wiki page
You can use the #ID control to link to a work item from within a Wiki page.
To learn more about the built-in wiki, see Add & edit wiki pages.