diff --git a/engine/src/engine.rs b/engine/src/engine.rs
index b0f11d05..b1986e87 100644
--- a/engine/src/engine.rs
+++ b/engine/src/engine.rs
@@ -22,10 +22,10 @@ use std::collections::HashMap;
 
 /// Represent a function type inside FCE.
 #[derive(Debug, serde::Serialize)]
-pub struct FCEFunction<'a> {
+pub struct FCEFunctionSignature<'a> {
     pub name: &'a str,
-    pub inputs: &'a Vec<IType>,
-    pub outputs: &'a Vec<IType>,
+    pub input_types: &'a Vec<IType>,
+    pub output_types: &'a Vec<IType>,
 }
 
 /// The base struct of the Fluence Compute Engine.
@@ -87,7 +87,7 @@ impl FCE {
     }
 
     /// Return function signatures of all loaded info FCE modules with their names.
-    pub fn interface(&self) -> impl Iterator<Item = (&str, Vec<FCEFunction<'_>>)> {
+    pub fn interface(&self) -> impl Iterator<Item = (&str, Vec<FCEFunctionSignature<'_>>)> {
         self.modules.iter().map(|(module_name, module)| {
             (
                 module_name.as_str(),
@@ -100,20 +100,20 @@ impl FCE {
     pub fn module_interface<S: AsRef<str>>(
         &self,
         module_name: S,
-    ) -> Result<Vec<FCEFunction<'_>>, FCEError> {
+    ) -> Result<Vec<FCEFunctionSignature<'_>>, FCEError> {
         match self.modules.get(module_name.as_ref()) {
             Some(module) => Ok(Self::get_module_function_signatures(module)),
             None => Err(FCEError::NoSuchModule),
         }
     }
 
-    fn get_module_function_signatures(module: &FCEModule) -> Vec<FCEFunction<'_>> {
+    fn get_module_function_signatures(module: &FCEModule) -> Vec<FCEFunctionSignature<'_>> {
         module
             .get_exports_signatures()
-            .map(|(name, inputs, outputs)| FCEFunction {
+            .map(|(name, input_types, output_types)| FCEFunctionSignature {
                 name,
-                inputs,
-                outputs,
+                input_types,
+                output_types,
             })
             .collect::<Vec<_>>()
     }
diff --git a/engine/src/lib.rs b/engine/src/lib.rs
index 3f843395..b65afd77 100644
--- a/engine/src/lib.rs
+++ b/engine/src/lib.rs
@@ -35,7 +35,7 @@ mod misc;
 
 pub use config::FCEModuleConfig;
 pub use engine::FCE;
-pub use engine::FCEFunction;
+pub use engine::FCEFunctionSignature;
 pub use errors::FCEError;
 pub use module::IValue;
 pub use module::IType;
diff --git a/fluence-faas/src/faas.rs b/fluence-faas/src/faas.rs
index f45d415f..a3d6de08 100644
--- a/fluence-faas/src/faas.rs
+++ b/fluence-faas/src/faas.rs
@@ -28,6 +28,7 @@ use fce::FCEModuleConfig;
 use std::convert::TryInto;
 use std::fs;
 use std::path::PathBuf;
+use crate::faas_interface::FaaSFunctionSignature;
 
 // TODO: remove and use mutex instead
 unsafe impl Send for FluenceFaaS {}
@@ -92,7 +93,7 @@ impl FluenceFaaS {
             if !path.is_dir() {
                 let module_name = path
                     .file_name()
-                    .ok_or(IOError(format!("No file name in path {:?}", path)))?
+                    .ok_or_else(|| IOError(format!("No file name in path {:?}", path)))?
                     .to_os_string()
                     .into_string()
                     .map_err(|name| IOError(format!("invalid file name: {:?}", name)))?;
@@ -137,7 +138,25 @@ impl FluenceFaaS {
 
     /// Return all export functions (name and signatures) of loaded on a startup modules.
     pub fn get_interface(&self) -> FaaSInterface {
-        let modules = self.fce.interface().collect();
+        let modules = self
+            .fce
+            .interface()
+            .map(|(name, signatures)| {
+                let signatures = signatures
+                    .iter()
+                    .map(|f| {
+                        (
+                            f.name,
+                            FaaSFunctionSignature {
+                                input_types: f.input_types,
+                                output_types: f.output_types,
+                            },
+                        )
+                    })
+                    .collect();
+                (name, signatures)
+            })
+            .collect();
 
         FaaSInterface { modules }
     }
diff --git a/fluence-faas/src/faas_interface.rs b/fluence-faas/src/faas_interface.rs
index 7bddf8d4..e128ad81 100644
--- a/fluence-faas/src/faas_interface.rs
+++ b/fluence-faas/src/faas_interface.rs
@@ -14,13 +14,21 @@
  * limitations under the License.
  */
 
+use super::IType;
+use serde::Serialize;
+
 use std::fmt;
 use std::collections::HashMap;
-use serde::Serialize;
 
 #[derive(Debug, Serialize)]
 pub struct FaaSInterface<'a> {
-    pub modules: HashMap<&'a str, Vec<fce::FCEFunction<'a>>>,
+    pub modules: HashMap<&'a str, HashMap<&'a str, FaaSFunctionSignature<'a>>>,
+}
+
+#[derive(Debug, Serialize)]
+pub struct FaaSFunctionSignature<'a> {
+    pub input_types: &'a Vec<IType>,
+    pub output_types: &'a Vec<IType>,
 }
 
 impl<'a> fmt::Display for FaaSInterface<'a> {
@@ -28,11 +36,11 @@ impl<'a> fmt::Display for FaaSInterface<'a> {
         for (name, functions) in self.modules.iter() {
             writeln!(f, "{}", *name)?;
 
-            for function in functions.iter() {
+            for (name, signature) in functions.iter() {
                 writeln!(
                     f,
                     "  pub fn {}({:?}) -> {:?}",
-                    function.name, function.inputs, function.outputs
+                    name, signature.input_types, signature.output_types
                 )?;
             }
         }