Letter of Recommendation for an MPP program? (Joint MBA/MPP applicants)

[wildchartermage]

I'm in the process of applying to MPP or related programs within the U.S, especially at top-tier programs like Harvard Kennedy School. I plan to pursue a joint MBA/MPP degree.

The MPP programs had asked for letters of recommendation (LOR).

Does anyone have tips, samples, or ideas of what makes a stellar letter of recommendation for a public policy program (MPP)?

So I can guide my recommenders because they've never written a LOR for a public policy program and had asked me for some guidance. Two are within academia and one is my client with a social impact business. TIA!