The minimum information should be:
- Excel sheet with a list of the hand tools you need designed
- Deliverables. Sketches, 3D CAD Design Intent, Prototypes,
- Timeline
Like Michael said, the more clear and complete your request is, the more accurate quotes you will receive. If you don’t provide enough information then companies will provide ballpark figures with a wide range. If this is what you are looking for, then be clear about it and that way the companies don’t spend a week writing a detailed proposal.
Once you select 2-3 that are in line with your budget you can disclose more detailed information in order to get a detailed proposal with costs, deliverables and timelines.
Good luck.