What makes a vulnerability finding useful, to the person fixing it?

When a pentest finding reaches a developer, they may not know what to do. The technical details of the vulnerability finding are not enough.

The vulnerability finding is more useful when it has steps to reproduce the problem, evidence of the vulnerability, and information about which parts of the system are affected by the vulnerability finding. It is also helpful to know how bad the impact of the vulnerability finding really is.

For people who work with pentest reports or vulnerability reports, what information do you think is most useful when you have to look into a vulnerability finding and fix the vulnerability finding?