diff --git a/bin/xclaude b/bin/xclaude
index b22d215..e354ed7 100755
--- a/bin/xclaude
+++ b/bin/xclaude
@@ -5,15 +5,22 @@
 import argparse
 import os
 import sys
+import urllib.parse
 
 env = os.environ
 
 
 def die(msg):
-    print(msg, file=sys.stderr)
+    print(f"Error: {msg}", file=sys.stderr)
     sys.exit(1)
 
-p = argparse.ArgumentParser(
+
+def validate_url(url):
+    parsed = urllib.parse.urlparse(url)
+    if parsed.scheme not in ("http", "https"):
+        die(f"invalid URL scheme '{parsed.scheme}' in --url (expected http or https)")
+
+parser = argparse.ArgumentParser(
     prog="xclaude",
     description="Run Claude Code with any OpenAI-compatible API backend.",
     epilog="""\
@@ -26,6 +33,8 @@ If neither URL nor token is set, defaults to Ollama:
   OLLAMA_HOST   - Ollama server address (default: nvidia.hell), or use --host
   OLLAMA_MODEL  - Ollama model (default: glm-5:cloud)
 
+Any extra arguments are passed through directly to the claude CLI.
+
 Examples:
   xclaude
   xclaude --model qwen3-coder
@@ -33,24 +42,26 @@ Examples:
 """,
     formatter_class=argparse.RawDescriptionHelpFormatter,
 )
-p.add_argument("--url", default=env.get("CLAUDE_URL", ""))
-p.add_argument("--token", default=env.get("CLAUDE_TOKEN", ""))
-p.add_argument("--model", default=env.get("CLAUDE_MODEL", ""))
-p.add_argument("--host", default=env.get("OLLAMA_HOST", "nvidia.hell"))
-args, rest = p.parse_known_args()
+parser.add_argument("--url", default=env.get("CLAUDE_URL", ""))
+parser.add_argument("--token", default=env.get("CLAUDE_TOKEN", ""))
+parser.add_argument("--model", default=env.get("CLAUDE_MODEL", ""))
+parser.add_argument("--host", default=env.get("OLLAMA_HOST", "nvidia.hell"))
+args, rest = parser.parse_known_args()
 
 env["DISABLE_TELEMETRY"] = "1"
 
 is_external_api = bool(args.url or args.token)
 if is_external_api:
     if not args.url:
-        die("Warning: no URL specified")
+        die("no URL specified (--url or CLAUDE_URL)")
+    validate_url(args.url)
     if not args.token:
-        die("Warning: no token specified")
+        die("no token specified (--token or CLAUDE_TOKEN)")
     if not args.model:
-        die("Warning: no model specified")
+        die("no model specified (--model or CLAUDE_MODEL)")
     env["ANTHROPIC_BASE_URL"] = args.url
     env["ANTHROPIC_API_KEY"] = args.token
+    # Remove Ollama auth token if switching to external API
     env.pop("ANTHROPIC_AUTH_TOKEN", None)
     model = args.model
 else:
@@ -58,7 +69,7 @@ else:
     model = args.model or env.get("OLLAMA_MODEL", "glm-5:cloud")
     env["ANTHROPIC_BASE_URL"] = f"http://{host}:11434"
     env["ANTHROPIC_AUTH_TOKEN"] = "ollama"
-    env["ANTHROPIC_API_KEY"] = ""
+    env.pop("ANTHROPIC_API_KEY", None)
 
 cmd = ["claude", "--model", model] + rest
 os.execvp("claude", cmd)