To validate collection data and indexes to look for inconsistencies, you use the validate function.
db.users.validate({full: true})
{
ns: 'test.users',
uuid: UUID('3f291365-864e-43d6-936a-cb74f8b34a0a'),
nInvalidDocuments: 0,
nNonCompliantDocuments: 0,
nrecords: 1,
nIndexes: 1,
keysPerIndex: { _id_: 1 },
indexDetails: { _id_: { valid: true } },
valid: true,
repaired: false,
warnings: [],
errors: [],
extraIndexEntries: [],
missingIndexEntries: [],
corruptRecords: [],
ok: 1
}