Part One: Strategy · The stance of the business
A promise is made by the person closest to the sale. It is kept, every day, by people who were never asked.
The front page says "set up in five minutes." The salesperson says the integration is "coming this quarter." The contract says support answers within the hour. Each sentence was written by someone whose work ends when the customer signs.
Then the customer arrives. Setup takes an afternoon. The integration is on no plan the developers have seen. Support answers within the hour, with a message saying a ticket has been opened. The customer now knows what the company's word is worth, and reads everything it says afterward with that in mind.
The people who pay first are inside the company. Support absorbs the anger for promises they never made. Developers are pulled off planned work to make a salesperson's sentence true. Either of them can ask to see the sales deck, mark each claim they would have to make true, and tell its author which ones they cannot.
A bold promise is fine when it is true. "Set up in five minutes" is a good line if a stranger can do it in five minutes. The trouble is the promise nobody can check: "seamless," "enterprise-grade," "coming soon." So the rule has two parts. A promise should be specific enough to be proved or disproved. And whoever has to keep it should approve it before it is made.
The second part is what changes behavior. A support lead who must sign off "answers within the hour" will ask what counts as an answer. A developer asked about "this quarter" will say which quarter.
The same honesty covers what the product does not do. SQLite, the database, publishes a page on when to use it and when to choose something else. That page makes the rest of the site easier to believe.
Therefore:
Make only promises specific enough to be checked, and let the people who must keep each one approve it first. Say just as plainly what the product does not do.
In practice. Collect every claim on the front page and in the sales deck. Beside each, write who has to make it true and whether they have been asked. Fix the ones where the answer is no.
Goes with. The first promise is made in SAY WHAT IT'S FOR (30). The one most often broken is a feature for ONE CUSTOMER'S REQUEST (24). When a promise fails anyway, OWN THE MISTAKE (53).