The brief is four pages of prose. Somewhere inside it, across various paragraphs, the client has named eleven competitors and linked to about thirty specific pages they admire or want to beat. That is the actual input to your work.
Getting the links out
Paste the whole document and extract the URLs. Thirty links appear as a list in seconds, without reading the brief a second time hunting for anchors you missed.
Then reduce to domains
Strip each URL to its domain and deduplicate. Thirty page links usually collapse to eight or nine distinct competitors, which is the number that actually matters for the analysis.
Why the reduction is the useful part
A brief that mentions the same three domains repeatedly and one domain once is telling you something about priority that the raw link list obscures. Counting how often each domain appears turns an unstructured document into a ranked list of who the client is really worried about.
Try it: Extract URLs from Text on SeoWolf's Notepad.