Safety-critical software-dependent systems such as those found in the avionics, automotive, maritime, and energy domains often need to be certified by a licensing or regulatory body based on one or more safety standards. Safety standards often do not specify the details of the evidence that needs to be collected for the certification of a particular system because these standards need to remain generic and applicable to a wide variety of systems and domains. Without an upfront agreement between the system supplier and the certifier about the details of the evidence that needs to be collected, there will invariably be important omissions in the evidence information provided by the supplier, which need to be remedied after the fact and at significant costs. In this paper, we present a flexible and tool-supported approach for assisting suppliers and certifiers in developing an agreement about the evidence necessary to demonstrate compliance to a safety standard. Our approach is model-based; specifically, the safety standard of interest is expressed via an information model. This helps manage the complexity of safety standards, provides precise interpretation for the standards, and ensures the completeness and consistency of the generated agreement.