how to check if tags dont exists

Question

hi everyone,

im trying to check if the inserted tags do not exists on the resource using a policy(policy to prevent somthing, unless it has the tags).
the tags are insert into an array parameter in the following format: Key;Value, Key;Value

this is the code i have:

 {
     "count": {
         "value": "[parameters('ExcludeTags')]",
         "name": "tag",
         "where": {
             "field": "[format('tags[{0}]',split(current('tag'),';')[0])]",
             "equals": "[split(current('tag'),';')[1]]"
          }
      },
      "equals": 0
},

but i get the following error when im deploying the policy:

The policy definition 'the policy id' rule is invalid. The 'field' property value '[format('tags[{0}]',split(current('tag'),';')[0])]' is invalid. 'field' and 'current' functions are not supported in the 'field' accessor.

does somebody know how to fix this?

thank you