A hundred-page brand book that nobody opens is not a brand system. For a small team, the useful deliverable is a short set of rules plus the files to apply them.
Constrain the palette and the type scale
Two typefaces and a palette of one brand colour, one ink, and a small neutral ramp cover nearly every layout a small team will produce.
Name the tokens by role rather than appearance — primary, surface, muted — so a future refresh does not require renaming everything.
Ship templates, not just rules
Give the team ready-made social sizes, a slide deck, an email header, and a document template. Guidelines describe the brand; templates are what actually keep it consistent.
Write the one-page rules sheet
Logo clear space, minimum size, what never to do, colour pairings that pass contrast, and where to find the files. One page, printable, and honest about the three mistakes people always make.