A brand guidelines document exists to answer one question: how do we show up consistently when the person who built the brand is not in the room? If your document cannot answer that question, it is not doing its job.
What most guidelines get wrong
Thin guidelines show the logo on a white background and call it done. Thick ones include 120 pages of rules no one reads past page 12. The right document is specific enough to guide real decisions and short enough to actually be consulted.
What to always include
Logo usage rules with clear spacing requirements, colour-safe versions, and what never to do. Colour system with exact HEX, RGB, CMYK, and Pantone values. Typography hierarchy showing which typefaces go where and at what sizes. Tone of voice: three to five adjectives that define how the brand sounds, with examples of on-brand and off-brand copy.
A brand guidelines document is not a museum piece. It is a working tool. If no one is using it, it is not the right document.
What you can leave out
Brand story, company history, and values manifestos belong in an internal culture document, not brand guidelines. Guidelines are for practitioners making visual and copy decisions. Keep it focused on the decisions they actually face.
Make it accessible
PDF is fine. A shared drive link is better. A Notion or Figma page that is always current is best. The format matters less than whether people can find it and actually use it.