added documentation

Author: wrisa

evaluators/contrib/galileo/src/agent_control_evaluator_galileo/llm/client.py

@@ -369,6 +369,8 @@ class GalileoLLMClient:
     """Thin HTTP client for Galileo LLM-as-judge scorer invocation.
 
     Environment Variables:
+        GALILEO_FEATURE_FLAG_LLM_INVOKE_RUNTIME: Set to ``enabled`` to activate the evaluator.
+            Required; the evaluator is unavailable until this flag is set.
         GALILEO_API_SECRET_KEY or GALILEO_API_SECRET: JWT signing secret for internal auth.
         GALILEO_LUNA_INVOKE_URL: LLM scorer invoke URL or service root (required).
         GALILEO_LUNA_INVOKE_CA_FILE: CA bundle used to verify invoke TLS.

sdks/python/src/agent_control/evaluators/__init__.py

@@ -16,6 +16,10 @@
     from agent_control.evaluators import LunaEvaluator, LunaEvaluatorConfig  # if galileo installed
     from agent_control.evaluators import LlmEvaluator, LlmEvaluatorConfig    # if galileo installed
     ```
+
+    Note: ``galileo.llm`` requires ``GALILEO_FEATURE_FLAG_LLM_INVOKE_RUNTIME=enabled`` to be set.
+    The evaluator is unavailable (``is_available()`` returns ``False``) until this flag is present,
+    as it depends on Orbit-side support for ``execution_context`` to fetch LLM credentials.
 """
 
 from agent_control_engine import (