AWS Elastic Transcoder - Return etag of transcoded file?

I'm using Elastic Transcoder in conjunction with Lambda and Step Functions to transcode MP3s from WAV files. I need to store the MD5 / S3 etag of the transcoded MP3s in my database. At the moment i'm having to fetch these using these in a separate process which is really slow:

s3_cli = boto3.client("s3",aws_access_key_id=ACCESS_KEY,aws_secret_access_key=SECRET_KEY)
s3_resp = s3_cli.head_object(Bucket=bucket, Key=mp3_key)
s3obj_etag = s3_resp['ETag'].replace('"', '')

Before putting this in place, I was hoping that Elastic Transcoder would provide the transcoded files etag in the job response, but I can not see this anywhere.

Does anyone have any tips on how to approach this better or am I missing something in the response/docs?

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