A project tells the model what you'd like. BeigeCheck checks what it did.

The cheapest way to give an AI tool your brand voice is the one you already pay for: a Claude Project, a set of ChatGPT custom instructions or a Copilot agent, holding a voice description and a few pasted facts. It costs nothing extra, it takes an afternoon, and for one person writing one kind of thing it’s often enough. BeigeCheck is for the point where that stops being true: several people, facts that change, more than one AI tool, and nobody checking the draft against any of it.

Side by side

Where they overlap

Both routes start from the same idea: the AI tool writes better when it knows who it’s writing for. A Claude Project with a good voice description and your best few pieces of writing in it will produce drafts that sound more like you than a blank chat does.

BeigeCheck doesn’t replace that. It’s a connector into the same Claude, ChatGPT and Copilot you’d set the project up in.

The vendors have made the do-it-yourself route better, too. Claude’s Team and Enterprise plans share a project with everyone in the organisation, with view and edit roles. ChatGPT’s Business plan shares projects and GPTs across a workspace. Microsoft lets an admin publish a Copilot agent to the whole company and approve each new version. For a team that writes one kind of thing in one tool, that’s a real option.

Where they differ

The first difference is what happens after the model writes. A project is an instruction. Nothing in Claude, ChatGPT or Copilot reads the draft back against the instruction and tells you where it went off, so the voice description that worked in March has stopped matching the drafts by June and nobody’s noticed. BeigeCheck checks every draft and shows you the sentences, with a score that moves when you fix them.

The second is facts. Pasted facts go stale. When your pricing changes, the number in the project instructions doesn’t, and ten people each keep their own wrong copy.

BeigeCheck holds one set of facts, each with its source and version. It gives the AI tool the ones this draft needs, then checks the draft’s claims against them.

The third is that a project doesn’t travel. The Claude Project doesn’t exist in ChatGPT, so when a colleague switches tools they rebuild the setup from memory. BeigeCheck’s knowledge is the same in all three.

And the fourth is who’s in charge of a change. In a shared project, anyone with edit access can change the instructions, and the change is live for everyone at once. In BeigeCheck, a change is a proposal until an approver says yes, and every yes is a version you can trace and undo.

Who each suits

If you’re one person, writing in one tool, about a business whose facts don’t change much, build the project. Put your voice description and your best writing in it, and keep it up to date yourself. You don’t need BeigeCheck yet, and we’d rather you found that out from us.

If several people write in the company’s name, if they use more than one AI tool between them, if your figures and client list change, or if you’ve been caught out by a draft that sounded fine and said something you can’t back, that’s what BeigeCheck is for.

Last checked 3 November 2026, against Anthropic’s, OpenAI’s and Microsoft’s own help and pricing pages. Prices and features change, so check theirs before you decide.