[{_id:1,name:"some name1",description:"some description1",parameters:[{name:"param name1",type:"param type1",default:"default value1"},{name:"param name2",type:"param type2",default:"default value2"}]},{_id:2,name:"some name2",description:"some description1",parameters:[{name:"param name21",type:"param type1",default:"default value1"},{name:"param name2",type:"param type2",default:"default value2"}]}]

db.collection.aggregate([{"$unwind":"$parameters"},{"$group":{"_id":"$_id","name":{"$first":"$name"},"description":{"$first":"$description"},"parameters":{"$push":{"name":"$parameters.name","parameter_type":"$parameters.type","value":"$parameters.default"}},}}])