fix(tools): unwrap FieldInfo default to avoid pydantic warning

Author: chaynabors

strands-py/src/strands/tools/decorator.py

@@ -163,8 +163,13 @@ def _extract_annotated_metadata(
         final_description = description
         if final_description is None:
             final_description = self.param_descriptions.get(param_name) or f"Parameter {param_name}"
-        # Create FieldInfo object from scratch
-        final_field = Field(default=param_default, description=final_description)
+        if isinstance(param_default, FieldInfo):
+            if param_default.description is None:
+                final_field = FieldInfo.merge_field_infos(param_default, FieldInfo(description=final_description))
+            else:
+                final_field = param_default
+        else:
+            final_field = Field(default=param_default, description=final_description)
 
         return actual_type, final_field