diff --git a/README.md b/README.md
index 1446aee..9946366 100644
--- a/README.md
+++ b/README.md
@@ -83,6 +83,24 @@ python src/paper_ingest.py
 
 **Starting the Application**
 
+Before starting your application, you need to fill in some evironment variables. Create a `.env` file and fill in these:
+
+```bash
+# LLM Provider
+OPENAI_API_KEY=
+GROQ_API_KEY= # (Optional)
+GOOGLE_API_KEY=
+
+# For Searching
+SERPER_API_KEY=
+
+# Email Sending
+SENDGRID_API_KEY= # (Optional)
+CHAINLIT_AUTH_SECRET=
+
+```
+You can create th `CHAINLIT_AUTH_SECRET` by running the command `chainlit create-secret`.
+
 Once everything is ready, you can launch the application by running:
 
 ```bash
diff --git a/app.py b/app.py
index bd5d5fa..347630c 100644
--- a/app.py
+++ b/app.py
@@ -1,4 +1,3 @@
-import sys
 from fastapi import FastAPI
 from dotenv import load_dotenv
 from api.controller import router
diff --git a/src/tools/paper_search_tool.py b/src/tools/paper_search_tool.py
index 1317015..482b30a 100644
--- a/src/tools/paper_search_tool.py
+++ b/src/tools/paper_search_tool.py
@@ -83,7 +83,7 @@ def retrieve_paper(query_str: str, start_date: str = None, end_date: str = None)
                     operator=FilterOperator.GTE, 
                     value=datetime.strptime(start_date, "%Y-%m-%d").timestamp()))
             
-        if end_date is not None:
+        if end_date is not None and end_date != '':
             filters.filters.append(
                 MetadataFilter(
                     key="date",