diff --git a/README.md b/README.md
index 0dd2ba428..92dd65330 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,18 @@ Configure other models, streaming, multi-document search, citations, and more.
 
 Drop PageIndex tools into the OpenAI Agents SDK, the Claude Agent SDK, or any other framework.
 
+### Indexing Markdown Documents via CLI
+
+PageIndex also supports indexing Markdown documents directly from the command line:
+
+```bash
+python3 run_pageindex.py --md_path document.md --if-add-node-summary yes
+```
+
+- `--summary-token-threshold <int>` (default: `200`): Cost optimization for Markdown indexing. When a node contains fewer tokens than this threshold, its raw text is copied verbatim into `summary` without an LLM call. Set to `0` to force LLM summary generation for all nodes.
+- `--if-thinning yes/no` (default: `no`): Whether to apply tree thinning for small Markdown sections.
+- `--thinning-threshold <int>` (default: `5000`): Minimum token threshold when tree thinning is enabled.
+
 
 # Benchmarks
 
diff --git a/pageindex/page_index_md.py b/pageindex/page_index_md.py
index 86ef2a145..184545b15 100644
--- a/pageindex/page_index_md.py
+++ b/pageindex/page_index_md.py
@@ -8,6 +8,12 @@
     from utils import *
 
 async def get_node_summary(node, summary_token_threshold=200, model=None):
+    """Generate summary for a markdown node.
+
+    For nodes whose text length is below summary_token_threshold (default: 200 tokens),
+    the raw node text is copied verbatim into summary without an LLM call to save costs.
+    Set summary_token_threshold=0 to force LLM summary generation for all nodes.
+    """
     node_text = node.get('text')
     num_tokens = count_tokens(node_text, model=model)
     if num_tokens < summary_token_threshold:
diff --git a/run_pageindex.py b/run_pageindex.py
index 8e3e1e525..20969b716 100644
--- a/run_pageindex.py
+++ b/run_pageindex.py
@@ -52,7 +52,7 @@
     parser.add_argument('--thinning-threshold', type=int, default=5000,
                       help='Minimum token threshold for thinning (markdown only)')
     parser.add_argument('--summary-token-threshold', type=int, default=200,
-                      help='Token threshold for generating summaries (markdown only)')
+                      help='Token threshold below which node text is copied verbatim into summary without an LLM call (default: 200, markdown only). Set to 0 to generate summaries for all nodes.')
     args = parser.parse_args()
     if args.flash:
         args.mode = 'flash'