This will allow you to get all the tags from the account.
TypeParametersValues
POSTcmd*retrieve_account_tags

* Required fields Here is an example:

'actions' => [
    '0' => [
        'cmd' => 'retrieve_account_tags'
    ]
]

Here are the results returned by the request:

ParametersValues
account_tagsString (JSON encoded array containing the names of all the tags in your account, empty array if no tags)
Example of the returned message:
{
    "status":"Success",
    "account_tags":[
        "Tag name 1",
        "Tag name 2"
    ]
}