diff --git a/CLAUDE.md b/CLAUDE.md
index 9e8db6d..f74c53c 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -11,7 +11,9 @@ This is a personal agenda web application built with Flask that tracks various e
 
 ## Python Environment
 - Always use `python3` directly, never `python`
-- Run `black` code formatter on modified code after creating or modifying Python files
+- All Python code should include type annotations
+- Use `typing.Any` instead of `Any` in type hints (import from typing module)
+- Run `mypy --strict` (fix any type errors in the file) and `black` on modified code after creating or modifying Python files
 - Avoid running `black .`
 - Main entry point: `python3 web_view.py` (Flask app on port 5000)
 - Tests: Use `pytest` (tests in `/tests/` directory)