diff --git a/specification/cognitiveservices/OpenAI.Inference/tspconfig.yaml b/specification/cognitiveservices/OpenAI.Inference/tspconfig.yaml
index b3d1870826b6..29557c0d3375 100644
--- a/specification/cognitiveservices/OpenAI.Inference/tspconfig.yaml
+++ b/specification/cognitiveservices/OpenAI.Inference/tspconfig.yaml
@@ -23,6 +23,8 @@ options:
     partial-update: true
     enable-sync-stack: true
     generate-tests: false
+    custom-types-subpackage: "implementation.models"
+    custom-types: "FunctionCallModelBase,FunctionCallPreset,FunctionCallPresetFunctionCallModel,FunctionDefinition,FunctionNameFunctionCallModel"
   # "@azure-tools/typespec-ts":
   #   package-dir: "azure-ai-openai"
   #   emitter-output-dir: "{project-root}/generated"