curl --request GET \
  --url https://api.mixpeek.com/v1/retrievers/{retriever_id} \
  --header 'Authorization: Bearer <token>' \
  --header 'X-Namespace: <x-namespace>'

{
  "budget_limits": {
    "max_credits": 100,
    "max_time_ms": 60000
  },
  "collection_ids": [
    "col_marketing_ads"
  ],
  "input_schema": {
    "query_text": {
      "description": "Full-text query",
      "type": "string"
    }
  },
  "retriever_id": "ret_abc123",
  "retriever_name": "executive_ads_search",
  "stages": [
    {
      "config": {
        "parameters": {
          "field": "metadata.spend",
          "operator": "gt",
          "value": 1000
        },
        "stage_name": "attribute_filter",
        "version": "v1"
      },
      "name": "filter_high_spend",
      "stage_type": "filter"
    }
  ]
}