It's hard to tell from your question what you have / don't have. Do you have an MVP? Do you have people using the 'discovery tool' yet?

It will be hard to get any restaurant to pay you anything unless you have a deployed MVP already. You'll need to show them actual data of the value of your tool. To do that you need people to be using it to find restaurants. So put restaurants into your tool without the restaurants necessarily paying anything for the listing. Once you have traffic you can start charging the restaurants for certain features.

That doesn't mean you should wait until your MVP is done before talking to restaurants though. To develop your MVP you should be visiting restaurants and talking to them about whether the features you're currently working on would be something they're actually interested in, and ask them open ended questions that may bring up ideas that you hadn't even thought of.

If you'd like more specific advice on the types of questions to ask, or what the restaurants might want to see in terms of MVP data, or general MVP development help, let me know,

best,

Lee