One note per candidate you ruled out, naming the exact thing and the date you checked it.
This is the slot the renewal reads, and it is the one nobody writes. "We looked at them and they weren't right" is what survives eighteen months, and it is worthless: it cannot be re-evaluated, because whatever was wrong may since have been fixed. A vendor disqualified in 2024 for lacking single sign-on, who shipped it in 2025, is a serious candidate again — and nobody will know.
So: what exactly, and when you checked. "No SAML SSO on any plan, confirmed with their sales engineer on 12 March" is a note whose shelf life you can reason about. Where the fact is point-in-time rather than structural, say so — that single distinction is what makes this slot reusable rather than merely archival, because it tells the next reader which entries need re-checking and which are settled.
Include the candidates ruled out early and cheaply. Those are the ones nobody documents and the ones most likely to have changed, since an early disqualification usually means an immature product rather than a wrong one.