diff --git a/cookbook/pageindex_RAG_simple.ipynb b/cookbook/pageindex_RAG_simple.ipynb
index 0bf4b29..fbfef47 100644
--- a/cookbook/pageindex_RAG_simple.ipynb
+++ b/cookbook/pageindex_RAG_simple.ipynb
@@ -40,12 +40,16 @@
       "cell_type": "markdown",
       "metadata": {},
       "source": [
-        "PageIndex generates a searchable tree structure of documents, enabling reasoning-based retrieval through tree search. \n",
+        "## Introduction\n",
+        "PageIndex is a new **vectorless RAG** framework. It conduct retrieval in two steps:  \n",
+        "1. Generate a tree structure to index documents  \n",
+        "2. Perform reasoning-based retrieval through tree search  \n",
         "\n",
         "<div align=\"center\">\n",
-        "  <img src=\"https://pageindex.ai/static/images/vectorless_rag_workflow.png\" width=\"100%\">\n",
+        "  <img src=\"https://pageindex.ai/static/images/vectorless_rag_workflow.png\" width=\"70%\">\n",
         "</div>\n",
         "\n",
+        "Compared to classic vector-based RAG, PageIndex features:\n",
         "- **No Vectors Needed**: Uses document structure and LLM reasoning for retrieval.\n",
         "- **No Chunking Needed**: Documents are organized into natural sections rather than artificial chunks.\n",
         "- **Human-like Retrieval**: Simulates how human experts navigate and extract knowledge from complex documents. \n",
@@ -61,21 +65,18 @@
         "This notebook demonstrates a simple example of **vectorless RAG** with PageIndex through the following steps:\n",
         "- [x] Build a PageIndex tree structure of a document\n",
         "- [x] Perform reasoning-based retrieval with tree search\n",
-        "- [x] Generate answers based on the retrieved context"
+        "- [x] Generate answers based on the retrieved context\n",
+        "\n",
+        "---"
       ]
     },
-    {
-      "cell_type": "markdown",
-      "metadata": {},
-      "source": []
-    },
     {
       "cell_type": "markdown",
       "metadata": {
         "id": "7ziuTbbWcG1L"
       },
       "source": [
-        "## Preparation\n",
+        "## Step 0: Preparation\n",
         "\n"
       ]
     },
@@ -85,7 +86,7 @@
         "id": "edTfrizMFK4c"
       },
       "source": [
-        "### Install dependencies"
+        "#### 0.1 Install dependencies"
       ]
     },
     {
@@ -106,7 +107,7 @@
         "id": "WVEWzPKGcG1M"
       },
       "source": [
-        "### Setup environment"
+        "#### 0.2 Setup environment"
       ]
     },
     {
@@ -134,7 +135,7 @@
         "id": "AR7PLeVbcG1N"
       },
       "source": [
-        "### Define utility functions"
+        "#### 0.3 Define utility functions"
       ]
     },
     {
@@ -198,7 +199,7 @@
         "id": "Mzd1VWjwMUJL"
       },
       "source": [
-        "### Submit a document with PageIndex SDK"
+        "#### 1.1 Submit a document with PageIndex SDK"
       ]
     },
     {
@@ -244,7 +245,7 @@
         "id": "4-Hrh0azcG1N"
       },
       "source": [
-        "### Get the generated PageIndex tree structure"
+        "#### 1.2 Get the generated PageIndex tree structure"
       ]
     },
     {
@@ -356,7 +357,7 @@
       "cell_type": "markdown",
       "metadata": {},
       "source": [
-        "### Use LLM for tree search and identify nodes that might contain relevant context"
+        "#### 2.1 Use LLM for tree search and identify nodes that might contain relevant context"
       ]
     },
     {
@@ -396,7 +397,7 @@
       "cell_type": "markdown",
       "metadata": {},
       "source": [
-        "### Print retrieved nodes and reasoning process"
+        "#### 2.2 Print retrieved nodes and reasoning process"
       ]
     },
     {
@@ -455,7 +456,7 @@
       "cell_type": "markdown",
       "metadata": {},
       "source": [
-        "### Extract relevant context from retrieved nodes"
+        "#### 3.1 Extract relevant context from retrieved nodes"
       ]
     },
     {
@@ -507,7 +508,7 @@
       "cell_type": "markdown",
       "metadata": {},
       "source": [
-        "### Generate answer based on retrieved context"
+        "#### 3.2 Generate answer based on retrieved context"
       ]
     },
     {