diff --git a/src/dipdup/codegen/substrate.py b/src/dipdup/codegen/substrate.py
index 1f7377837..d5cc2d5f6 100644
--- a/src/dipdup/codegen/substrate.py
+++ b/src/dipdup/codegen/substrate.py
@@ -83,9 +83,10 @@ def event_metadata_to_jsonschema(
     metadata: dict[str, Any],
 ) -> dict[str, Any]:
     description = '\n'.join(metadata['docs']).replace(r'\[', '[').replace(r'\]', ']')
-    args_name = [a for a in metadata.get('args_name', ()) if a]
+    args_name = tuple(a for a in metadata.get('args_name', ()) if a)
     if not args_name:
-        args_name = extract_args_name(description)  # type: ignore[assignment]
+        args_name = extract_args_name(tuple(metadata['docs']))
+
     schema = {
         '$schema': 'http://json-schema.org/draft-07/schema#',
         'title': metadata['name'],
diff --git a/src/dipdup/runtimes.py b/src/dipdup/runtimes.py
index ce4d3f6f6..d4e288a40 100644
--- a/src/dipdup/runtimes.py
+++ b/src/dipdup/runtimes.py
@@ -1,5 +1,4 @@
 import logging
-import re
 from contextlib import suppress
 from copy import copy
 from functools import cache
@@ -24,13 +23,13 @@
 
 
 @cache
-def extract_args_name(docs: list[str]) -> tuple[str, ...]:
+def extract_args_name(docs: tuple[str, ...]) -> tuple[str, ...]:
     docs_str = ''.join(docs).replace('\\n', '').replace('\n', '')
 
     # find the last bracket pair, [] or ()
     open_bracket = max(docs_str.rfind('['), docs_str.rfind('('))
     close_bracket = max(docs_str.rfind(']'), docs_str.rfind(')'))
-    slice = docs_str[open_bracket + 1:close_bracket]
+    slice = docs_str[open_bracket + 1 : close_bracket]
 
     return tuple(arg.strip('\\ ') for arg in slice.split(','))
 
@@ -74,7 +73,8 @@ def get_event_abi(self, qualname: str) -> dict[str, Any]:
                         continue
                     self._events[qualname] = event
                     found = True
-            else:
+
+            if not found:
                 raise FrameworkException(f'Event `{qualname}` not found in `{self._name}` spec')
 
         return self._events[qualname]
@@ -86,7 +86,7 @@ def get_event_arg_names(event_abi: dict[str, Any]) -> tuple[str, ...]:
 
     # NOTE: Old metadata
     if not arg_names:
-        arg_names = extract_args_name(event_abi['docs'])
+        arg_names = extract_args_name(tuple(event_abi['docs']))
 
     return tuple(arg_names)
 
@@ -175,7 +175,6 @@ def decode_event_args(
 
             args = dict(zip(arg_names, args, strict=True))
 
-
         payload = {}
         for (key, value), type_ in zip(args.items(), arg_types, strict=True):
             if isinstance(value, int):