From 462c1c14dde090ce7596905bf556e3894fc30abe Mon Sep 17 00:00:00 2001
From: teknium1 <127238744+teknium1@users.noreply.github.com>
Date: Sat, 19 Sep 2026 00:04:49 -0700
Subject: [PATCH] fix(tools): tool_call bridge treats blank arguments as no
 arguments

Some OpenAI-compatible gateways emit `arguments: ""` (or whitespace) for a
tool whose schema has no required parameters. On the tool_search bridge path
(`normalize_tool_call_entries`) that string went straight into json.loads and
every attempt failed with "arguments is not valid JSON: Expecting value ...",
so the model retried the same call forever and the tool never ran (#83937).

Treat a blank string like the already-accepted `None`: it means {}. The
outer-loop already does this for the top-level tool_call arguments string
(turn_tool_validation), so the bridge was the only surface left rejecting the
shape; a tool with required params still gets the proper "missing required"
hint from validate_deferred_call_args, and malformed non-blank JSON keeps
failing closed (#61784 intent intact).

Co-authored-by: webtecnica <webtecnica@gmail.com>
---
 tests/tools/test_tool_search.py | 11 +++++++++++
 tools/tool_search_validation.py |  6 +++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/tests/tools/test_tool_search.py b/tests/tools/test_tool_search.py
index cd77ed8149..e44da62f14 100644
--- a/tests/tools/test_tool_search.py
+++ b/tests/tools/test_tool_search.py
@@ -471,6 +471,17 @@ class TestBridgeDispatch:
         assert err is not None
         assert "bridge tool" in err.lower()
 
+    @pytest.mark.parametrize("raw_args", ["", "  \n", None])
+    def test_resolve_underlying_call_treats_blank_arguments_as_no_arguments(self, raw_args):
+        """An OpenAI-compatible gateway emitting ``arguments: ""`` for a parameterless deferred tool
+        must execute with {} instead of looping on a JSON parse error (#83937); malformed
+        non-blank arguments still fail closed."""
+        from tools.tool_search import resolve_underlying_call
+        name, args, err = resolve_underlying_call({"calls": [{"name": "todo_list", "arguments": raw_args}]})
+        assert (name, args, err) == ("todo_list", {}, None)
+        _, _, err = resolve_underlying_call({"calls": [{"name": "todo_list", "arguments": '{"todos": ['}]})
+        assert err and "not valid JSON" in err
+
 
 # ---------------------------------------------------------------------------
 # End-to-end via the real handle_function_call (smoke test).
diff --git a/tools/tool_search_validation.py b/tools/tool_search_validation.py
index a0cc28c67d..fb62f87977 100644
--- a/tools/tool_search_validation.py
+++ b/tools/tool_search_validation.py
@@ -173,7 +173,11 @@ def normalize_tool_call_entries(args: Dict[str, Any]) -> Tuple[List[Dict[str, An
         if name in BRIDGE_TOOL_NAMES:
             return [], f"tool_call cannot invoke '{name}' (it is itself a bridge tool)"
         raw_args = raw.get("arguments")
-        if raw_args is None:
+        if raw_args is None or (isinstance(raw_args, str) and not raw_args.strip()):
+            # "" / whitespace is how some OpenAI-compatible gateways spell "no arguments" for a
+            # parameterless tool (#83937); the loop already treats an empty outer arguments string
+            # as {} (turn_tool_validation), and a missing required param still surfaces below via
+            # validate_deferred_call_args instead of an opaque JSON parse error.
             raw_args = {}
         if isinstance(raw_args, str):
             try: