diff --git a/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/localservice/DafnyLocalServiceTypeConversionProtocol.java b/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/localservice/DafnyLocalServiceTypeConversionProtocol.java
index d2a1dd25d..e1f68a0c0 100644
--- a/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/localservice/DafnyLocalServiceTypeConversionProtocol.java
+++ b/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/localservice/DafnyLocalServiceTypeConversionProtocol.java
@@ -446,11 +446,7 @@ public void generateOrphanShapeSerializer(
     final Set<ShapeId> alreadyVisited,
     ServiceShape serviceShape
   ) {
-    if (alreadyVisited.contains(shape.toShapeId())) {
-      return;
-    }
-    // We don't need type conversion for operation shape and resource shape
-    if (shape.isOperationShape() || shape.isResourceShape()) {
+    if (GoCodegenUtils.shapeShouldHaveConversionFunction(shape) == false || alreadyVisited.contains(shape.toShapeId())) {
       return;
     }
     if (shape.hasTrait(UnitTypeTrait.class)) {
@@ -952,10 +948,7 @@ public void generateOrphanShapeDeserializer(
     final Set<ShapeId> alreadyVisited,
     ServiceShape serviceShape
   ) {
-    if (alreadyVisited.contains(shape.toShapeId())) {
-      return;
-    }
-    if (shape.isOperationShape() || shape.isResourceShape()) {
+    if (GoCodegenUtils.shapeShouldHaveConversionFunction(shape) == false || alreadyVisited.contains(shape.toShapeId())) {
       return;
     }
     if (shape.hasTrait(UnitTypeTrait.class)) {
diff --git a/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/utils/GoCodegenUtils.java b/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/utils/GoCodegenUtils.java
index 00fc41ffa..9b56d02ed 100644
--- a/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/utils/GoCodegenUtils.java
+++ b/codegen/smithy-dafny-codegen/src/main/java/software/amazon/polymorph/smithygo/utils/GoCodegenUtils.java
@@ -6,6 +6,8 @@
 import software.amazon.polymorph.smithygo.codegen.SymbolUtils;
 import software.amazon.polymorph.smithygo.localservice.nameresolver.DafnyNameResolver;
 import software.amazon.polymorph.smithygo.localservice.nameresolver.SmithyNameResolver;
+import software.amazon.polymorph.smithypython.awssdk.nameresolver.AwsSdkNameResolver;
+import software.amazon.smithy.model.traits.ErrorTrait;
 import software.amazon.polymorph.traits.PositionalTrait;
 import software.amazon.polymorph.traits.ReferenceTrait;
 import software.amazon.smithy.aws.traits.ServiceTrait;
@@ -188,4 +190,34 @@ private static String getInputOrOutputName(
       );
     }
   }
+  
+  /**
+   * Returns true if a conversion function should be written for the shape, false otherwise.
+   * Conversion functions are only written for "complex" shapes:
+   *  - StructureShapes ("complex" because StructureShapes can be recursive)
+   *    - except for non-AWS SDK StructureShapes with ErrorTrait; these aren't "complex"
+   *  - UnionShapes ("complex" because the conversion is not a one-liner)
+   *  - EnumShapes or StringShapes with EnumTrait ("complex" because the conversion is not a one-liner)
+   * @param shape
+   * @return
+   */
+  public static boolean shapeShouldHaveConversionFunction(Shape shape) {
+    if (shape.isStructureShape()) {
+      if (
+        !SmithyNameResolver.isShapeFromAWSSDK(shape) &&
+        shape.hasTrait(ErrorTrait.class)
+      ) {
+        return false;
+      }
+      return true;
+    } else if (shape.isUnionShape()) {
+      return true;
+    } else if (
+      (shape.isStringShape() && shape.hasTrait(EnumTrait.class)) ||
+      shape.isEnumShape()
+    ) {
+      return true;
+    }
+    return false;
+  }
 }