MQTT json attribute template

Hi,
I try to setup MQTT json attribute template as below. The value template returns correct value but I could not get attribute in json format even with dumb texts. It returns error message Erroneous JSON: { “test”: ok, “verify”: fail }.
Btw, is there any way to debug MQTT sensor without restarting HA or reloading MQTT.yaml ? Similar to Developer tools/Template tab, I can wonder if I can send MQTT payload and get returned value_template/ json_attributes_template result

-   name: "Timestamp_raw"
    state_topic: "5a1b33a2bc/events/rpc"
    value_template: "{{  value_json.params.ts}}"
    unique_id: "TimeStamp_raw"
    json_attributes_topic: "5a1b33a2bc/events/rpc"
    json_attributes_template:  >
        { "test": {{"ok"}},
          "verify": {{"fail"}} }

Hi Ngkhanh,

MQTT, at least the manual ones, can be reloaded using the reload all button or individually be typing c in the dashboard and searching for mqtt.

image

Thanks, I knew about service option but want to check if there is an option to interact directly with MQTT module on HA core through REST or python API ? We just want to get output given JSON payload of MQTT message.