How to confirm a SFP is bad and needs to be replaced

Hi Team,

Whenever we get any link failure alerts or any message of that type, most of the time we go for SFP replacement.

We also use the command, show int fcx/y transceiver details.  The output gives the Tx and Rx power for that particular SFP.

Is there any standard value for Tx and Rx ? So if the Tx and Rx are below that standard value then do we need to consider replacing the SFP ? If so could anyone tell what are those standard values ?