diff --git a/etc/devtools_parser.py b/etc/devtools_parser.py
index 1c10c9c5a8b..c006415a74b 100755
--- a/etc/devtools_parser.py
+++ b/etc/devtools_parser.py
@@ -6,7 +6,7 @@
 
 # This is a script designed to easily debug devtools messages
 # It takes the content of a pcap wireshark capture (or creates a new
-# one when using --scan) and pretty prints the JSON payloads.
+# one when using `-w`) and prints the JSON payloads.
 #
 # Wireshark (more specifically its cli tool tshark) needs to be installed
 # for this script to work. Go to https://tshark.dev/setup/install for a
@@ -17,25 +17,24 @@
 # MacOS (With homebrew):      brew install --cask wireshark
 # Windows (With chocolatey):  choco install wireshark
 #
-# To use it, launch either Servo or a Firefox debugging instance in
-# devtools mode:
+# To use it, launch Servo or Firefox in devtools mode:
 #
-# Servo: ./mach run --devtools=1234
-# Firefox: firefox --new-instance --start-debugger-server 1234 --profile PROFILE
+# Servo: ./mach run --devtools 6080
+# Firefox: firefox --new-instance --start-debugger-server 6080 --profile PROFILE
 #
-# Then run this tool in capture mode and specify the same port as before:
+# Then run this tool in capture mode, specifying the same port as before:
 #
-# ./devtools_parser.py --scan cap.pcap --port 1234
+# ./devtools_parser.py -w capture.pcap -p 6080
 #
-# Finally, open another instance of Firefox and go to about:debugging
-# and connect to localhost:1234. Messages should start popping up. The
-# scan can be finished by pressing Ctrl+C. Then, all of the messages will
-# show up.
+# Finally, open another instance of Firefox, go to about:debugging and connect
+# to localhost:6080. Messages should start popping up. The scan can be finished
+# by pressing Ctrl+C. After that the messages will be printed.
 #
-# You can also review the results of a saved scan, and filter by words
-# or by message range:
+# To review the results of the scan use the `-r` flag. It is possible to output
+# newline-delimited JSON for further processing with other tools using the
+# `--json` flag.
 #
-# ./devtools_parser.py --use cap.pcap --port 1234 --filter watcher --range 10:30
+# ./devtools_parser.py -r capture.pcap --json > capture.json
 
 import json
 import signal
@@ -171,33 +170,26 @@ def parse_message(msg, json_output=False):
 if __name__ == "__main__":
     # Program arguments
     parser = ArgumentParser()
-    parser.add_argument("-p", "--port", default="1234", help="the port where the devtools client is running")
-    parser.add_argument("-f", "--filter", help="search for the string on the messages")
-    parser.add_argument("-r", "--range", help="only parse messages from n to m, with the form of n:m")
+    parser.add_argument("-p", "--port", default="6080", help="the port where the devtools client is running")
     parser.add_argument("--json", action="store_true", help="output in newline-delimited JSON (NDJSON)")
 
     actions = parser.add_mutually_exclusive_group(required=True)
-    actions.add_argument("-s", "--scan", help="scan and save the output to a file")
-    actions.add_argument("-u", "--use", help="use the scan from a file")
+    actions.add_argument(
+        "-w", "--write-file", help="capture messages on the specified port and write the output to a .pcap file"
+    )
+    actions.add_argument("-r", "--read-file", help="parse the captured messages from a .pcap file")
 
     args = parser.parse_args()
 
     # Run tshark, either to start a capture or to read an already existing pcap file
-    if args.scan:
-        capture_args = ["-i", "lo", "-f", f"tcp port {args.port}", "-w", args.scan]
+    if args.write_file:
+        capture_args = ["-i", "lo", "-f", f"tcp port {args.port}", "-w", args.write_file]
         data = tshark(capture_args, wait=True)
     else:
-        read_args = ["-r", args.use]
+        read_args = ["-r", args.read_file]
         data = tshark(read_args)
 
     data = process_data(data)
 
-    # Set the range of messages to show
-    min, max = 0, -2
-    if args.range and len(args.range.split(":")) == 2:
-        min, max = args.range.split(":")
-
-    for msg in data[int(min) : int(max) + 1]:
-        # Filter the messages if specified
-        if not args.filter or args.filter.lower() in msg[3].lower():
-            parse_message(msg, json_output=args.json)
+    for msg in data:
+        parse_message(msg, json_output=args.json)
diff --git a/etc/devtools_parser_test.json b/etc/devtools_parser_test.json
index b5bb1fe2b67..e8e636d42b3 100644
--- a/etc/devtools_parser_test.json
+++ b/etc/devtools_parser_test.json
@@ -57,3 +57,4 @@
 {"to": "server1.conn0.thread-configuration15", "configuration": {"shouldPauseOnDebuggerStatement": true}, "type": "updateConfiguration"}
 {"from": "server1.conn0.thread-configuration15"}
 {"to": "server1.conn0.thread-configuration15", "configuration": {"pauseOnExceptions": false, "ignoreCaughtExceptions": false}, "type": "updateConfiguration"}
+{"from": "server1.conn0.thread-configuration15"}
diff --git a/python/servo/testing_commands.py b/python/servo/testing_commands.py
index 9c0626c18c2..f1fd87f565a 100644
--- a/python/servo/testing_commands.py
+++ b/python/servo/testing_commands.py
@@ -369,7 +369,7 @@ class MachCommands(CommandBase):
         if platform.system() == "Linux":
             try:
                 result = subprocess.run(
-                    ["etc/devtools_parser.py", "--json", "--use", "etc/devtools_parser_test.pcap"],
+                    ["etc/devtools_parser.py", "--json", "--read-file", "etc/devtools_parser_test.pcap"],
                     check=True,
                     capture_output=True,
                 )