diff --git a/CLAUDE.md b/CLAUDE.md
index 6c342b8..3d86bef 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -222,7 +222,13 @@ export MODEL_API_KEY_3=dummy
 
 ## Creating Activity YAML Files - Expert Guide
 
-**IMPORTANT: Before creating or modifying any activity YAML files, ALWAYS read `research/SPEC.yaml` first to ensure you have the latest specification and examples.**
+**IMPORTANT: Before creating or modifying any activity YAML files:**
+1. **ALWAYS read `research/SPEC.yaml` first** to ensure you have the latest specification and examples
+2. **ALWAYS validate the YAML after creating/modifying** by running:
+   ```bash
+   python activity_yaml_validator.py research/your_activity.yaml
+   ```
+3. **All activity YAMLs MUST pass validation** with 0 errors before committing
 
 When creating activities for OpenCompletion, follow these expert guidelines to ensure your activities **validate properly**, are **FUN and engaging**, and **terminate correctly**.