diff --git a/PLAN.md b/PLAN.md
index 44778b9..335f635 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -65,9 +65,9 @@ Create a netviel clone with improvements:
 ## Phase 6: Polish
 - [ ] Add proper error handling throughout
 - [ ] Add logging
-- [ ] Update README with usage instructions
-- [ ] Add configuration options (NOTMUCH_PATH env var)
-- [ ] Security audit and warnings (local-only usage)
+- [x] Update README with usage instructions
+- [x] Add configuration options (NOTMUCH_PATH env var)
+- [x] Security audit and warnings (local-only usage)
 - [ ] Run `zig fmt .`
 
 ## Notes
diff --git a/README.md b/README.md
index 06723f9..6b974f8 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,20 @@
 Zetviel
 -------
 
-As some background, I've had some issues with the very usable [netviel](https://github.com/DavidMStraub/netviel).
+A web-based email client for [notmuch](https://notmuchmail.org/), written in Zig.
 
-I wanted to address those issues, but also simplify the deployment. And, I like zig,
+As some background, I've had some issues with the very usable [netviel](https://github.com/DavidMStraub/netviel).
+I wanted to address those issues, but also simplify the deployment. And, I like Zig,
 so I decided this was small enough I'd just re-write the thing to make my own.
 
-This is still very work in progress, to the point it is not yet usable. It has
-some basic notmuch integration and a usable build system.
+Features
+--------
+
+- REST API for notmuch queries
+- Thread and message viewing
+- Attachment handling
+- Security headers for safe browsing
+- Configurable port
 
 Building
 --------
@@ -18,4 +25,39 @@ will install the necessary notmuch header/library, and the build system will
 detect and use that. Again, `zig build` will work in that instance, but you must
 `nix develop` first.
 
-More to come...
+Usage
+-----
+
+```sh
+# Start server on default port (5000)
+zetviel
+
+# Start server on custom port
+zetviel --port 8080
+
+# Show help
+zetviel --help
+
+# Show version
+zetviel --version
+```
+
+Configuration
+-------------
+
+- `NOTMUCH_PATH` environment variable: Path to notmuch database (default: `mail`)
+- `--port`: HTTP server port (default: 5000)
+
+API Endpoints
+-------------
+
+- `GET /api/query/<query>` - Search threads using notmuch query syntax
+- `GET /api/thread/<thread_id>` - Get messages in a thread
+- `GET /api/message/<message_id>` - Get message details with content
+- `GET /api/attachment/<message_id>/<num>` - Get attachment metadata
+
+Security
+--------
+
+**WARNING**: Zetviel is intended for local use only. It binds to 127.0.0.1 and should
+not be exposed to the internet without additional security measures.