diff --git a/calculator/README.md b/calculator/README.md
new file mode 100644
index 0000000..af69754
--- /dev/null
+++ b/calculator/README.md
@@ -0,0 +1 @@
+# calculator
\ No newline at end of file
diff --git a/calculator/lorem.txt b/calculator/lorem.txt
new file mode 100644
index 0000000..900ea57
--- /dev/null
+++ b/calculator/lorem.txt
@@ -0,0 +1 @@
+wait, this isn't lorem ipsum
\ No newline at end of file
diff --git a/calculator/test_output.txt b/calculator/test_output.txt
new file mode 100644
index 0000000..95d09f2
--- /dev/null
+++ b/calculator/test_output.txt
@@ -0,0 +1 @@
+hello world
\ No newline at end of file
diff --git a/functions/call_function.py b/functions/call_function.py
new file mode 100644
index 0000000..40eb3e8
--- /dev/null
+++ b/functions/call_function.py
@@ -0,0 +1,57 @@
+import os
+from google.genai import types
+
+from functions.get_files_info import get_files_info
+from functions.get_file_content import get_file_content
+from functions.write_file import write_file
+from functions.run_python_file import run_python_file
+
+
+def call_function(function_call_part, verbose=False):
+
+    function_name = function_call_part.name
+    args = dict(function_call_part.args or {})
+
+    args["working_directory"] = "./calculator"
+
+    function_map = {
+        "get_files_info": get_files_info,
+        "get_file_content": get_file_content,
+        "write_file": write_file,
+        "run_python_file": run_python_file,
+    }
+
+    if verbose:
+        print(f"Calling function: {function_name}({args})")
+    else:
+        print(f" - Calling function: {function_name}")
+
+    if function_name not in function_map:
+        return types.Content(
+            role="tool",
+            parts=[
+                types.Part.from_function_response(
+                    name=function_name,
+                    response={"error": f"Unknown function: {function_name}"},
+                )
+            ],
+        )
+
+    try:
+        function_result = function_map[function_name](**args)
+    except Exception as e:
+        function_result = f"Error executing function: {e}"
+
+    tool_response = types.Content(
+        role="tool",
+        parts=[
+            types.Part.from_function_response(
+                name=function_name, response={"result": function_result}
+            )
+        ],
+    )
+
+    if verbose:
+        print(f"-> {tool_response.parts[0].function_response.response}")
+
+    return tool_response
\ No newline at end of file
diff --git a/main.py b/main.py
index 88ad19f..42b1774 100644
--- a/main.py
+++ b/main.py
@@ -3,6 +3,7 @@ import sys
 from dotenv import load_dotenv
 from google import genai
 from google.genai import types
+from functions.call_function import call_function
 from functions.get_files_info import schema_get_files_info
 from functions.get_file_content import schema_get_file_content
 from functions.run_python_file import schema_run_python_file
@@ -75,14 +76,17 @@ def main():
     if response.candidates[0].content.parts:
         for part in response.candidates[0].content.parts:
             if part.function_call:
-                function_call_part = part.function_call
-                print(f"Calling function: {function_call_part.name}({function_call_part.args})")
+                function_result = call_function(part.function_call, verbose=verbose)
+                # validate that function call produced a response
+                if not (
+                    function_result.parts
+                    and function_result.parts[0].function_response
+                    and function_result.parts[0].function_response.response
+                ):
+                    raise RuntimeError("Fatal: Function call returned no response.")
             elif part.text:
                 reply_text = part.text
-
-                # Add AI response to history
                 add_message("model", reply_text)
-
                 print(reply_text)
 
     if verbose: