Short Answer

Initially, you should provide the minimal information required.

Detailed Answer

The minimal information is:

• ASSEMBLYNAME: Unique assembly name
• COVERAGE: The estimated depth of sequencing coverage
• PROGRAM: The assembly program

Optional information includes:

• MINGAPLENGTH: Minimum length of consecutive Ns to be considered a gap
• MOLECULETYPE: ‘genomic DNA’, ‘genomic RNA’ or ‘viral cRNA’
• DESCRIPTION: Free text description of the genome assembly

Further information to the respective ENA docs here.