diff --git a/src/pdl/pdl_stdlib.pdl b/src/pdl/pdl_stdlib.pdl
index 5ab7b9c2d..99e930c9c 100644
--- a/src/pdl/pdl_stdlib.pdl
+++ b/src/pdl/pdl_stdlib.pdl
@@ -23,17 +23,26 @@ defs:
     function:
       model: string
       prompt: string
+      parameters: {optional: object}
     return:
+      defs:
+        parameters: ${ parameters | default({}) }
+        params: 
+          data: 
+            logprobs: true
+            top_logprobs: 5
+            response_format: {'type': 'json_schema', 'json_schema': {'name': 'schema', 'schema': {'enum': [True, False]}, 'strict': True}}
       lastOf:
+      - lang: python
+        def: final_parameters
+        code: |
+          result = parameters | params
       - model: ${ model }
+        def: evaluation
         input: |
           ${ prompt }
         modelResponse: out
-        parameters:
-          temperature: 0
-          logprobs: true
-          top_logprobs: 5
-          response_format: {'type': 'json_schema', 'json_schema': {'name': 'schema', 'schema': {'enum': [True, False]}, 'strict': True}}
+        parameters: ${ final_parameters }
       - def: score
         data: ${ reward(response=out) }
       retry: 3