diff --git a/calculator/main.py b/calculator/main.py
index beb4cec..737148e 100644
--- a/calculator/main.py
+++ b/calculator/main.py
@@ -2,7 +2,6 @@ import sys
 from pkg.calculator import Calculator
 from pkg.render import render
 
-
 def main():
     calculator = Calculator()
     if len(sys.argv) <= 1:
diff --git a/functions/get_file_content.py b/functions/get_file_content.py
index 1fc90c0..1f3919a 100644
--- a/functions/get_file_content.py
+++ b/functions/get_file_content.py
@@ -1,5 +1,21 @@
 import os
 from functions.config import MAX_FILE_CONTENT_CHARS
+from google.genai import types
+
+schema_get_file_content = types.FunctionDeclaration(
+    name="get_file_content",
+    description="Reads and returns the contents of a file, truncated if too large, constrained to the working directory.",
+    parameters=types.Schema(
+        type=types.Type.OBJECT,
+        properties={
+            "file_path": types.Schema(
+                type=types.Type.STRING,
+                description="Path to the file, relative to the working directory.",
+            ),
+        },
+        required=["file_path"],
+    ),
+)
 
 
 def get_file_content(working_directory, file_path):
diff --git a/functions/get_files_info.py b/functions/get_files_info.py
index 21f9523..da9dc05 100644
--- a/functions/get_files_info.py
+++ b/functions/get_files_info.py
@@ -1,4 +1,19 @@
 import os
+from google.genai import types
+
+schema_get_files_info = types.FunctionDeclaration(
+    name="get_files_info",
+    description="Lists files in the specified directory along with their sizes, constrained to the working directory.",
+    parameters=types.Schema(
+        type=types.Type.OBJECT,
+        properties={
+            "directory": types.Schema(
+                type=types.Type.STRING,
+                description="The directory to list files from, relative to the working directory. If not provided, lists files in the working directory itself.",
+            ),
+        },
+    ),
+)
 
 def get_files_info(working_directory, directory="."):
     try:
diff --git a/functions/run_python_file.py b/functions/run_python_file.py
index f85316e..678834f 100644
--- a/functions/run_python_file.py
+++ b/functions/run_python_file.py
@@ -1,6 +1,26 @@
 import os
 import subprocess
+from google.genai import types
 
+schema_run_python_file = types.FunctionDeclaration(
+    name="run_python_file",
+    description="Executes a Python file with optional arguments, constrained to the working directory.",
+    parameters=types.Schema(
+        type=types.Type.OBJECT,
+        properties={
+            "file_path": types.Schema(
+                type=types.Type.STRING,
+                description="Path to the Python file, relative to the working directory.",
+            ),
+            "args": types.Schema(
+                type=types.Type.ARRAY,
+                description="List of arguments to pass to the Python script.",
+                items=types.Schema(type=types.Type.STRING),
+            ),
+        },
+        required=["file_path"],
+    ),
+)
 
 def run_python_file(working_directory, file_path, args=[]):
     try:
diff --git a/functions/write_file.py b/functions/write_file.py
index be8c43f..5972353 100644
--- a/functions/write_file.py
+++ b/functions/write_file.py
@@ -1,4 +1,24 @@
 import os
+from google.genai import types
+
+schema_write_file = types.FunctionDeclaration(
+    name="write_file",
+    description="Writes or overwrites file contents within the working directory.",
+    parameters=types.Schema(
+        type=types.Type.OBJECT,
+        properties={
+            "file_path": types.Schema(
+                type=types.Type.STRING,
+                description="Path to the file relative to the working directory.",
+            ),
+            "content": types.Schema(
+                type=types.Type.STRING,
+                description="The text content to write into the file.",
+            ),
+        },
+        required=["file_path", "content"],
+    ),
+)
 
 
 def write_file(working_directory, file_path, content):
diff --git a/main.py b/main.py
index d00f4de..88ad19f 100644
--- a/main.py
+++ b/main.py
@@ -3,6 +3,39 @@ import sys
 from dotenv import load_dotenv
 from google import genai
 from google.genai import types
+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
+from functions.write_file import schema_write_file
+
+available_functions = types.Tool(
+    function_declarations=[
+        schema_get_files_info,
+        schema_get_file_content,
+        schema_run_python_file,
+        schema_write_file,
+    ]
+)
+
+system_prompt = """
+You are a helpful AI coding agent.
+
+When a user asks a question or makes a request, make a function call plan. 
+You can perform the following operations:
+
+- List files and directories
+- Read file contents
+- Execute Python files with optional arguments
+- Write or overwrite files
+
+All paths you provide should be relative to the working directory. 
+You do not need to specify the working directory in your function calls 
+as it is automatically injected for security reasons.
+"""
+
+config=types.GenerateContentConfig(
+    tools=[available_functions], system_instruction=system_prompt
+)
 
 messages = []
 
@@ -35,15 +68,22 @@ def main():
 
     response = client.models.generate_content(
         model="gemini-2.0-flash-001",
-        contents=messages
+        contents=messages,
+        config=config,
     )
 
-    reply_text = response.text
+    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})")
+            elif part.text:
+                reply_text = part.text
 
-    # Add AI response to history
-    add_message("model", reply_text)
+                # Add AI response to history
+                add_message("model", reply_text)
 
-    print(reply_text)
+                print(reply_text)
 
     if verbose:
         print(f"Prompt tokens: {response.usage_metadata.prompt_token_count}")