diff --git a/datasette/cli.py b/datasette/cli.py
index 22e2338a..12d3d728 100644
--- a/datasette/cli.py
+++ b/datasette/cli.py
@@ -136,6 +136,12 @@ def cli():
 @click.option("--inspect-file", default="-")
 @sqlite_extensions
 def inspect(files, inspect_file, sqlite_extensions):
+    """
+    Generate JSON summary of provided database files
+
+    This can then be passed to "datasette --inspect-file" to speed up count
+    operations against immutable database files.
+    """
     app = Datasette([], immutables=files, sqlite_extensions=sqlite_extensions)
     loop = asyncio.get_event_loop()
     inspect_data = loop.run_until_complete(inspect_(files, sqlite_extensions))
diff --git a/docs/cli-reference.rst b/docs/cli-reference.rst
index adf89633..7ac6debe 100644
--- a/docs/cli-reference.rst
+++ b/docs/cli-reference.rst
@@ -51,7 +51,7 @@ datasette --help
 
     Commands:
       serve*     Serve up specified SQLite database files with a web UI
-      inspect
+      inspect    Generate JSON summary of provided database files
       install    Install Python packages - e.g.
       package    Package specified SQLite files into a new datasette Docker...
       plugins    List currently available plugins
@@ -317,6 +317,11 @@ datasette inspect --help
 
     Usage: datasette inspect [OPTIONS] [FILES]...
 
+      Generate JSON summary of provided database files
+
+      This can then be passed to "datasette --inspect-file" to speed up count
+      operations against immutable database files.
+
     Options:
       --inspect-file TEXT
       --load-extension TEXT  Path to a SQLite extension to load