curl --request GET \
  --url https://{host}/v3/llm-gateway/providers/options \
  --header 'Authorization: Bearer <token>'

{
  "api": "v3",
  "data": [
    {
      "provider": "openai",
      "display_name": "OpenAI",
      "credential_types": [
        "api_key"
      ],
      "models": [
        "gpt-5",
        "gpt-4",
        "gpt-4o-mini",
        "gpt-3.5-turbo"
      ]
    },
    {
      "provider": "anthropic",
      "display_name": "Anthropic",
      "credential_types": [
        "api_key"
      ],
      "models": [
        "sonnet-3.7",
        "haiku-3",
        "opus-3"
      ]
    },
    {
      "provider": "vertex_ai",
      "display_name": "Vertex AI",
      "credential_types": [
        "gcp_service_account"
      ],
      "models": [
        "gemini-2.5-pro",
        "gemini-2.5-flash"
      ]
    }
  ]
}