**To change the description of a model in an API**

Command::

  aws apigateway update-model --rest-api-id 1234123412 --model-name 'Empty' --patch-operations op=replace,path=/description,value='New Description'

**To change the schema of a model in an API**

Command::

  aws apigateway update-model --rest-api-id 1234123412 --model-name 'Empty' --patch-operations op=replace,path=/schema,value='"{ \"$schema\": \"http://json-schema.org/draft-04/schema#\", \"title\" : \"Empty Schema\", \"type\" : \"object\" }"'