Retrofit + Moshi - NoJsonAdapter Found

java.lang.IllegalArgumentException: No JsonAdapter for retrofit2.Call<xxxxx.data.adapter.ActivationResponse> (with no annotations)
     Message: Unable to create converter for retrofit2.Call<xxxxx.data.adapter.ActivationResponse>
        for method ActivationService.postActivationPayload

I am getting this error when trying to use Moshi alongside Retrofit for handling a request

package xxxx.data.adapter
import com.squareup.moshi.JsonClass

@JsonClass(generateAdapter = true)
data class ActivationResponse(
    var status: String,
    var statusCode: String?,
    var description: String?
)

interface ActivationService { 
@POST("/") // substitute real path
    suspend fun postActivationPayload(@Body activationPayloadPost: ActivationPayloadPost) : Call<ActivationResponse>
}

Here is the activation service im supplying into Retrofit

@JsonClass(generateAdapter = true)
data class ActivationPayloadPost(
    var id: String,
    var status: String?
)

Have I just completely missed a step with working with Moshi and Retrofit? I thought it was supposed to be able to read simple types on its own.

Here is the call for retro

        val BASE_URL = "xxxxx"
        val retrofit = Retrofit.Builder()
            .baseUrl(BASE_URL)
            .addConverterFactory(MoshiConverterFactory.create(moshi))
            .build()
        val activationService = retrofit.create(ActivationService::class.java)

I have already tested that my moshi object is able to use moshi.adapter(ActivationPayloadPost::class.java) .toJSON and it IS able to render the output I need, but when running through Retro its giving me this error.