diff --git a/packages/cli/package.json b/packages/cli/package.json
index 64897e6..b7d6b0f 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -1,7 +1,6 @@
 {
   "name": "@typelex/cli",
   "version": "0.2.0",
-  "description": "CLI for typelex - TypeSpec-based IDL for ATProto Lexicons",
   "main": "dist/index.js",
   "type": "module",
   "bin": {
diff --git a/packages/cli/src/cli.ts b/packages/cli/src/cli.ts
index 807c682..f2cbdeb 100644
--- a/packages/cli/src/cli.ts
+++ b/packages/cli/src/cli.ts
@@ -13,17 +13,31 @@ async function main() {
       (yargs) => {
         return yargs
           .positional("namespace", {
-            describe: "Primary namespace pattern (e.g., app.bsky.*)",
+            describe: "Primary namespace pattern (e.g., com.example.*)",
             type: "string",
             demandOption: true,
           })
           .option("out", {
-            describe: "Output directory for generated Lexicon files (relative to cwd)",
+            describe: "Output directory for generated Lexicon files (must end with 'lexicons')",
             type: "string",
             default: "./lexicons",
           });
       },
       async (argv) => {
+        if (!argv.namespace) {
+          console.error("Error: namespace is required");
+          console.error("Usage: typelex compile <namespace>");
+          console.error("Example: typelex compile com.example.*");
+          process.exit(1);
+        }
+
+        if (!argv.namespace.endsWith(".*")) {
+          console.error("Error: namespace must end with .*");
+          console.error(`Got: ${argv.namespace}`);
+          console.error("Example: typelex compile com.example.*");
+          process.exit(1);
+        }
+
         const options: Record<string, unknown> = {};
         if (argv.watch) {
           options.watch = true;
@@ -39,12 +53,16 @@ async function main() {
       type: "boolean",
       default: false,
     })
-    .demandCommand(1, "You must specify a command")
+    .demandCommand(1)
     .help()
     .version()
     .fail((msg, err) => {
       if (err) {
         console.error(err);
+      } else if (msg.includes("Not enough non-option arguments")) {
+        console.error("Error: namespace is required");
+        console.error("Usage: typelex compile <namespace>");
+        console.error("Example: typelex compile com.example.*");
       } else {
         console.error(msg);
       }