diff --git a/mace/examples/cli/example.cc b/mace/examples/cli/example.cc
index ec93674e8ec680605742cd61a9556d42ea7bd291..4892baf2e3a1dbc69f688b76a34f7d7a7a21f7dd 100644
--- a/mace/examples/cli/example.cc
+++ b/mace/examples/cli/example.cc
@@ -113,7 +113,7 @@ DEFINE_string(opencl_parameter_file,
               "tuned OpenCL parameter file path");
 DEFINE_string(model_data_file,
               "",
-              "model data file name, used when EMBED_MODEL_DATA set to 0");
+              "model data file name, used when model_data_format == file");
 DEFINE_string(model_file,
               "",
               "model file name, used when load mace model in pb");
@@ -194,9 +194,11 @@ bool RunModel(const std::vector<std::string> &input_names,
   // Create Engine
   std::shared_ptr<mace::MaceEngine> engine;
   MaceStatus create_engine_status;
-  // Only choose one of the two type based on the `build_type`
+  // Only choose one of the two type based on the `model_graph_format`
   // in model deployment file(.yml).
 #ifdef MODEL_GRAPH_FORMAT_CODE
+  // if model_data_format == code, just pass an empty string("")
+  // to model_data_file parameter.
   create_engine_status =
       CreateMaceEngineFromCode(FLAGS_model_name,
                                FLAGS_model_data_file,
diff --git a/mace/public/mace.h b/mace/public/mace.h
index 9a35da5bd1afb3e26d9b0bb9908072bd3572b4ee..f6116348f7f5874021271fd04feb680c615df4c7 100644
--- a/mace/public/mace.h
+++ b/mace/public/mace.h
@@ -127,6 +127,19 @@ class __attribute__((visibility("default"))) MaceEngine {
   MaceEngine &operator=(const MaceEngine &) = delete;
 };
 
+/// \brief Create MaceEngine from files (model file + data file)
+///
+/// Create MaceEngine object
+///
+/// \param model_pb[in]: the content of model graph file
+/// \param model_data_file[in]: the path of model data file
+/// \param input_nodes[in]: the array of input nodes' name
+/// \param output_nodes[in]: the array of output nodes' name
+/// \param device_type[in]: one of [CPU, GPU, HEXAGON],
+///        based on the runtime type of your model deployment file.
+/// \param engine[out]: output MaceEngine object
+/// \return MACE_SUCCESS for success, MACE_INVALID_ARGS for wrong arguments,
+///         MACE_OUT_OF_RESOURCES for resources is out of range.
 __attribute__((visibility("default")))
 MaceStatus CreateMaceEngineFromProto(
     const std::vector<unsigned char> &model_pb,
diff --git a/mace/python/tools/mace_engine_factory.h.jinja2 b/mace/python/tools/mace_engine_factory.h.jinja2
index e1a81753f23d33c54a13fc45134be4b7145406cd..472879365035bfe8a9ac945766dd559e94d72bf4 100644
--- a/mace/python/tools/mace_engine_factory.h.jinja2
+++ b/mace/python/tools/mace_engine_factory.h.jinja2
@@ -47,6 +47,21 @@ std::map<std::string, int> model_name_map {
 };
 }  // namespace
 
+/// \brief Create MaceEngine from code
+///
+/// Create MaceEngine object based on model graph code and model data file or
+/// model data code.
+///
+/// \param model_name[in]: the name of model you want to use.
+/// \param model_data_file[in]: the path of model data file,
+///        if model_data_format is code, just pass empty string("")
+/// \param input_nodes[in]: the array of input nodes' name
+/// \param output_nodes[in]: the array of output nodes' name
+/// \param device_type[in]: one of [CPU, GPU, HEXAGON],
+///        based on the runtime type of your model deployment file.
+/// \param engine[out]: output MaceEngine object
+/// \return MACE_SUCCESS for success, MACE_INVALID_ARGS for wrong arguments,
+///         MACE_OUT_OF_RESOURCES for resources is out of range.
 MaceStatus CreateMaceEngineFromCode(
     const std::string &model_name,
     const std::string &model_data_file,