diff --git a/llama_stack/apis/scoring_functions/scoring_functions.py b/llama_stack/apis/scoring_functions/scoring_functions.py
index 52508d2ec..aba597bf3 100644
--- a/llama_stack/apis/scoring_functions/scoring_functions.py
+++ b/llama_stack/apis/scoring_functions/scoring_functions.py
@@ -28,11 +28,37 @@ from llama_stack.schema_utils import json_schema_type, register_schema, webmetho
 # with standard metrics so they can be rolled up?
 @json_schema_type
 class ScoringFnParamsType(Enum):
+    """
+    A type of scoring function parameters.
+
+    :cvar llm_as_judge: Provide judge model and prompt template.
+    :cvar regex_parser: Provide regexes to parse the answer from the generated response.
+    :cvar basic: Parameters for basic non-parameterized scoring function.
+    """
+
     llm_as_judge = "llm_as_judge"
     regex_parser = "regex_parser"
     basic = "basic"
 
 
+@json_schema_type
+class ScoringFunctionType(Enum):
+    """
+    A type of scoring function. Each type is a criteria for evaluating answers.
+
+    :cvar llm_as_judge: Scoring function that uses a judge model to score the answer.
+    :cvar regex_parser: Scoring function that parses the answer from the generated response using regexes, and checks against the expected answer.
+    """
+
+    llm_as_judge = "llm_as_judge"
+    regex_parser = "regex_parser"
+    # NOTE: add additional scoring function types that can be registered
+    # equality = "equality"
+    # subset_of = "subset_of"
+    # valid_json = "valid_json"
+    # text_quality = "text_quality"
+
+
 @json_schema_type
 class AggregationFunctionType(Enum):
     average = "average"
@@ -43,7 +69,7 @@ class AggregationFunctionType(Enum):
 
 @json_schema_type
 class LLMAsJudgeScoringFnParams(BaseModel):
-    type: Literal[ScoringFnParamsType.llm_as_judge.value] = ScoringFnParamsType.llm_as_judge.value
+    type: Literal["llm_as_judge"] = "llm_as_judge"
     judge_model: str
     prompt_template: Optional[str] = None
     judge_score_regexes: Optional[List[str]] = Field(
@@ -58,9 +84,9 @@ class LLMAsJudgeScoringFnParams(BaseModel):
 
 @json_schema_type
 class RegexParserScoringFnParams(BaseModel):
-    type: Literal[ScoringFnParamsType.regex_parser.value] = ScoringFnParamsType.regex_parser.value
+    type: Literal["regex_parser"] = "regex_parser"
     parsing_regexes: Optional[List[str]] = Field(
-        description="Regex to extract the answer from generated response",
+        description="Regexes to extract the answer from generated response",
         default_factory=list,
     )
     aggregation_functions: Optional[List[AggregationFunctionType]] = Field(
@@ -71,7 +97,7 @@ class RegexParserScoringFnParams(BaseModel):
 
 @json_schema_type
 class BasicScoringFnParams(BaseModel):
-    type: Literal[ScoringFnParamsType.basic.value] = ScoringFnParamsType.basic.value
+    type: Literal["basic"] = "basic"
     aggregation_functions: Optional[List[AggregationFunctionType]] = Field(
         description="Aggregation functions to apply to the scores of each row",
         default_factory=list,
@@ -140,10 +166,18 @@ class ScoringFunctions(Protocol):
     @webmethod(route="/scoring-functions", method="POST")
     async def register_scoring_function(
         self,
-        scoring_fn_id: str,
-        description: str,
-        return_type: ParamType,
-        provider_scoring_fn_id: Optional[str] = None,
-        provider_id: Optional[str] = None,
+        scoring_fn_type: ScoringFunctionType,
         params: Optional[ScoringFnParams] = None,
-    ) -> None: ...
+        scoring_fn_id: Optional[str] = None,
+        description: Optional[str] = None,
+    ):
+        """
+        Register a new scoring function with given parameters.
+        Only valid scoring function type that can be parameterized can be registered.
+
+        :param scoring_fn_type: The type of scoring function to register. A function type can only be registered if it is a valid type.
+        :param params: The parameters for the scoring function.
+        :param scoring_fn_id: (Optional) The ID of the scoring function to register. If not provided, a random ID will be generated.
+        :param description: (Optional) The description of the scoring function.
+        """
+        ...