diff --git a/servers/custom/src/custom.py b/servers/custom/src/custom.py
index f7e61a86..c7fa2e87 100644
--- a/servers/custom/src/custom.py
+++ b/servers/custom/src/custom.py
@@ -48,7 +48,7 @@ def r1_searcher_query_extract(ans_ls: List[str]) -> Dict[str, List[str]]:
     """
 
     def get_query(text):
-        pattern = re.compile(r"<|begin_of_query|>([^<]*)", re.DOTALL)
+        pattern = re.compile(r"<\|begin_of_query\|>([^<]*)", re.DOTALL)
         matches = pattern.findall(text)
 
         if matches:
diff --git a/tests/servers/custom/test_query_extract.py b/tests/servers/custom/test_query_extract.py
new file mode 100644
index 00000000..febf4df3
--- /dev/null
+++ b/tests/servers/custom/test_query_extract.py
@@ -0,0 +1,43 @@
+"""Tests for the query-extraction tools in the ``custom`` MCP server.
+
+The ``custom`` server lives under ``servers/custom/src`` rather than inside the
+installable ``ultrarag`` package, so its module is made importable here without
+installing each server separately.
+"""
+
+import sys
+from pathlib import Path
+
+CUSTOM_SRC = Path(__file__).resolve().parents[3] / "servers" / "custom" / "src"
+sys.path.insert(0, str(CUSTOM_SRC))
+
+import custom  # noqa: E402
+
+
+def test_r1_searcher_query_extract_returns_tagged_query():
+    answers = [
+        "Let me reason about this. "
+        "<|begin_of_query|>capital of France<|end_of_query|> then continue."
+    ]
+    result = custom.r1_searcher_query_extract(answers)
+    assert result == {"extract_query_list": ["capital of France?"]}
+
+
+def test_r1_searcher_query_extract_uses_last_query():
+    answers = [
+        "<|begin_of_query|>first question<|end_of_query|> ... "
+        "<|begin_of_query|>second question<|end_of_query|> done."
+    ]
+    result = custom.r1_searcher_query_extract(answers)
+    assert result == {"extract_query_list": ["second question?"]}
+
+
+def test_r1_searcher_query_extract_appends_question_mark():
+    answers = ["<|begin_of_query|>already a question?<|end_of_query|>"]
+    result = custom.r1_searcher_query_extract(answers)
+    assert result == {"extract_query_list": ["already a question?"]}
+
+
+def test_r1_searcher_query_extract_without_tag():
+    result = custom.r1_searcher_query_extract(["no query tags in this text"])
+    assert result == {"extract_query_list": ["There is no query."]}