curl -g -D @tags.json "https://api.softlayer.com/rest/v3/SoftLayer_Virtual_Guest/1626036/setTags"

tags.json

{
 "parameters":[
        "tag1, tag2, tag3",
 ]
}

I had moderate success with this call:
curl -X POST --data @tags.json "https://api.softlayer.com/rest/v3/SoftLayer_Virtual_Guest/3919126/setTags"

and this tags.json (note the correction to the array definition):
{
"parameters":[
"tag1",
"tag2",
"tag3"
]
}

The result was that the first tag appeared in the portal, but not tag2/tag3

In order for the additional tags to work, the initial value needs to be comma separated with no double quote breaks between them. I was able to get this example to work:

{
"parameters":["tag1,tag2,tag3"]
}

It is important to note that the tags are replaced and not appended to so it would be a good idea to get the existing tags before you update them.

@rhodgin @rbraddes: Apologies just now seeing these comments. I am looking into this. There seems to be a bug causing the API to return true even when the call fails when using setTags.

I cannot get multiple tags to work, only one.

I've tried every variant shown on this page, but I never see more than one tag in the instance data.

Any help valued!!