i need help to make a consumble item

i need help here whats i got so far {
  "criteria": {
    "idk": {
      "trigger": "minecraft:consume_item",
      "conditions": {
        "item": {
          "items": "minecraft:echo_shard",
          "count": 1,
          "predicates": {
            "minecraft:custom_data": "{"custom_id": "warden_key"}"
          }
        }
      }
    }
  },
  "requirements": [
    [
      "idk"
    ]
  ],
  "rewards": {
    "function": "warden_kingdom:key"
  },
  "sends_telemetry_event": false
}