docs: document default mode shortcuts for save and get

- Quick Start: show bare keep <tag> (save) and keep <#> (get) shortcuts
- Save Mode: note that --save is optional when piping content
- Get Mode: clarify that only numeric IDs default to Get mode;
  fix incorrect keep <tag> example that would actually save

README.md

@@ -134,10 +134,13 @@ cargo build --release --features server,client,swagger
 ## Quick Start
 
 ```sh
-# Save content with a tag
-echo "Hello, world!" | keep --save greeting
+# Save content with a tag (--save is optional when piping)
+echo "Hello, world!" | keep greeting
 
-# Retrieve by tag
+# Retrieve by ID (--get is optional for numeric IDs)
+keep 1
+
+# Retrieve by tag (--get is required for tags)
 keep --get greeting
 
 # List all stored items
@@ -176,14 +179,15 @@ keep --list --meta project=myapp
 
 ### Save Mode
 
-Save stdin content with tags and metadata.
+Save stdin content with tags and metadata. The `--save` flag is optional when piping content.
 
 ```sh
 # Save (auto-assigned ID, no tag)
 echo "data" | keep --save
 
-# Save with a tag
+# Save with a tag (--save is optional when piping)
 echo "data" | keep --save my-tag
+echo "data" | keep my-tag
 
 # Save with multiple tags and metadata
 cat report.pdf | keep --save report --meta project=alpha --meta env=prod
@@ -196,16 +200,15 @@ Tags and metadata make items easy to find later. Tags are simple identifiers; me
 
 ### Get Mode
 
-Retrieve items by ID or tags. This is the default mode when IDs are provided.
+Retrieve items by ID. This is the default mode when numeric IDs are provided.
 
 ```sh
-# Get by ID
+# Get by ID (no --get needed for numeric IDs)
 keep --get 1
 keep 1
 
-# Get by tag
+# Get by tag (requires --get flag)
 keep --get my-tag
-keep my-tag
 
 # Get with filters applied
 keep --get 1 --filters "head_lines(10)"