diff --git a/pgmon.py b/pgmon.py
index 1cb2749..6275e88 100755
--- a/pgmon.py
+++ b/pgmon.py
@@ -178,8 +178,8 @@ class Request:
     """
     A metric request
     """
-    def __init__(self, key, args = {}):
-        self.key = key
+    def __init__(self, metric_name, args = {}):
+        self.metric_name = metric_name
         self.args = args
         self.result = None
 
@@ -322,14 +322,14 @@ class Agent:
     The agent side of the connector
     """
     @staticmethod
-    def run(config, key, args):
+    def run(config, key):
         # Connect to the socket
         ipc = IPC(config, 'agent')
         try:
             conn = ipc.connect()
 
             # Send a request
-            ipc.send(conn, "{},{}".format(key, args))
+            ipc.send(conn, key)
 
             # Wait for a response
             res = ipc.recv(conn)
@@ -379,26 +379,30 @@ class Server:
                 continue
 
             # Get the request string (csv)
-            req_csv = ipc.recv(conn)
+            key = ipc.recv(conn)
 
-            # Receive ipc request (csv)
+            # Parse ipc request (csv)
             try:
-                (key, args_str) = req_csv.split(',', 1)
+                parts = key.split(',', 1)
+                metric_name = parts[0]
                 args_dict = {}
-                if args_str is not None and args_str != "":
-                    for (k, v) in [a.split('=', 1) for a in args_str.split(';')]:
+
+                if len(parts) > 1:
+                    for arg in parts[1].split(','):
+                        (k, v) = arg.split('=', 1)
                         args_dict[k] = v
             except socket.timeout:
                 print("IPC communication timeout receiving request")
                 conn.close()
                 continue
             except Exception:
-                print("Received invalid request: '{}'".format(req_csv))
+                print("Received invalid request: '{}'".format(key))
+                ipc.send(conn, "ERROR: Invalid key")
                 conn.close()
                 continue
 
             # Create request object
-            req = Request(key, args_dict)
+            req = Request(metric_name, args_dict)
 
             # Queue the request
             try:
@@ -447,9 +451,9 @@ class Worker(threading.Thread):
 
             # Find the requested metrtic
             try:
-                metric = self.config.metrics[req.key]
+                metric = self.config.metrics[req.metric_name]
             except KeyError:
-                req.set_result("ERROR: Unknown key '{}'".format(req.key))
+                req.set_result("ERROR: Unknown key '{}'".format(req.metric_name))
                 continue
 
             # Get the DB version
@@ -528,21 +532,20 @@ def main():
     parser.add_argument('-v', '--verbose', action='store_true')
 
     # Operational mode
-    parser.add_argument('-m', '--mode', choices=['agent', 'server'], required=True)
+    parser.add_argument('-s', '--server', action='store_true')
 
     # Agent options
-    parser.add_argument('-k', '--key')
-    parser.add_argument('-a', '--args')
+    parser.add_argument('key', nargs='?')
 
     args = parser.parse_args()
 
-    if args.mode == 'agent':
-        config = Config(args.config, read_metrics = False)
-        Agent.run(config, args.key, args.args)
-
-    else:
+    if args.server:
         config = Config(args.config)
         Server.run(config)
+    else:
+        config = Config(args.config, read_metrics = False)
+        Agent.run(config, args.key)
+
 
 if __name__ == '__main__':
     main()
@@ -560,13 +563,13 @@ class TestRequest:
     def test_request_creation(self):
         # Create result with no args
         req1 = Request('foo', {})
-        assert req1.key == 'foo'
+        assert req1.metric_name == 'foo'
         assert len(req1.args) == 0
         assert req1.complete.locked()
 
         # Create result with args
         req2 = Request('foo', {'arg1': 'value1', 'arg2': 'value2'})
-        assert req2.key == 'foo'
+        assert req2.metric_name == 'foo'
         assert len(req2.args) == 2
         assert req2.complete.locked()
 
diff --git a/pgmon_userparameter.conf b/pgmon_userparameter.conf
index 1850a4b..f582b49 100644
--- a/pgmon_userparameter.conf
+++ b/pgmon_userparameter.conf
@@ -1 +1 @@
-UserParameter=pgmon[*],/usr/local/bin/pgmon.py -c /etc/zabbix/pgmon.cfg -k "$1" -a "$2"
+UserParameter=pgmon[*],/usr/local/bin/pgmon.py -c /etc/zabbix/pgmon.cfg "$0"