diff --git a/tests/test_application.py b/tests/test_application.py
new file mode 100644
index 0000000..800f4a5
--- /dev/null
+++ b/tests/test_application.py
@@ -0,0 +1,65 @@
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import Mock, patch
+from zoneinfo import ZoneInfo
+
+from assistant_bot import application as application_module
+from assistant_bot.auth import authentication_guard
+from assistant_bot.handlers import (
+    ask_command,
+    help_command,
+    history_command,
+    inline_query,
+    model_command,
+    models_command,
+    new_conversation_command,
+    private_text,
+    private_voice,
+    start,
+)
+
+
+class ApplicationRegistrationTests(unittest.TestCase):
+    def test_registers_the_current_public_handlers_in_order(self) -> None:
+        with tempfile.TemporaryDirectory() as directory, patch.multiple(
+            application_module,
+            get_assistant_password=Mock(return_value="secret"),
+            get_bot_token=Mock(return_value="123456:TEST"),
+            get_db_path=Mock(
+                return_value=Path(directory) / "assistant.sqlite3"
+            ),
+            get_assistant_mode=Mock(return_value="local"),
+            get_ollama_base_url=Mock(return_value="http://localhost:11434"),
+            get_whisper_model=Mock(return_value="small"),
+            get_whisper_device=Mock(return_value="cpu"),
+            get_whisper_compute_type=Mock(return_value="int8"),
+            get_whisper_language=Mock(return_value="ru"),
+            get_local_timezone=Mock(return_value=ZoneInfo("UTC")),
+            get_voice_max_duration_seconds=Mock(return_value=120),
+        ):
+            application = application_module.create_application()
+
+        self.assertEqual(
+            [handler.callback for handler in application.handlers[-1]],
+            [authentication_guard],
+        )
+        self.assertEqual(
+            [handler.callback for handler in application.handlers[0]],
+            [
+                start,
+                help_command,
+                ask_command,
+                models_command,
+                model_command,
+                new_conversation_command,
+                history_command,
+                inline_query,
+                private_voice,
+                private_text,
+            ],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/test_core.py b/tests/test_core.py
index 49b4aa3..87dd823 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -6,7 +6,11 @@ from datetime import datetime, timezone
 from pathlib import Path
 from zoneinfo import ZoneInfo
 
-from assistant_bot.agent import execute_agent_tool, parse_agent_decision
+from assistant_bot.agent import (
+    build_agent_tool_prompt,
+    execute_agent_tool,
+    parse_agent_decision,
+)
 from assistant_bot.reminders import parse_reminder, unit_to_timedelta
 from assistant_bot.storage import AssistantStorage
 
@@ -52,6 +56,144 @@ class AgentDecisionTests(unittest.TestCase):
         self.assertTrue(decision.reset_context)
 
 
+class AgentToolContractTests(unittest.TestCase):
+    TOOL_NAMES = (
+        "get_current_datetime",
+        "remember",
+        "list_memory",
+        "delete_memory",
+        "create_note",
+        "list_notes",
+        "delete_note",
+        "create_reminder",
+        "list_reminders",
+        "cancel_reminder",
+        "create_status",
+        "list_statuses",
+        "update_status",
+        "delete_status",
+        "search_conversation",
+    )
+
+    def test_prompt_exposes_all_supported_tool_names(self) -> None:
+        prompt = build_agent_tool_prompt(ZoneInfo("UTC"))
+
+        for tool_name in self.TOOL_NAMES:
+            with self.subTest(tool_name=tool_name):
+                self.assertIn(tool_name, prompt)
+
+    def test_crud_tool_result_shapes_remain_stable(self) -> None:
+        with tempfile.TemporaryDirectory() as directory:
+            storage = AssistantStorage(Path(directory) / "assistant.sqlite3")
+            common = {
+                "storage": storage,
+                "user_id": 42,
+                "chat_id": 100,
+                "tz": ZoneInfo("UTC"),
+            }
+
+            memory = execute_agent_tool(
+                "remember",
+                {"text": "короткие ответы"},
+                **common,
+            )
+            self.assertEqual(
+                memory,
+                {"ok": True, "id": memory["id"], "text": "короткие ответы"},
+            )
+            self.assertEqual(
+                execute_agent_tool("list_memory", {"limit": 10}, **common)[
+                    "items"
+                ][0]["id"],
+                memory["id"],
+            )
+            self.assertEqual(
+                execute_agent_tool(
+                    "delete_memory",
+                    {"id": memory["id"]},
+                    **common,
+                ),
+                {"ok": True, "id": memory["id"]},
+            )
+
+            note = execute_agent_tool(
+                "create_note",
+                {"text": "идея"},
+                **common,
+            )
+            self.assertEqual(
+                note,
+                {"ok": True, "id": note["id"], "text": "идея"},
+            )
+            self.assertEqual(
+                execute_agent_tool("list_notes", {}, **common)["items"][0][
+                    "id"
+                ],
+                note["id"],
+            )
+            self.assertEqual(
+                execute_agent_tool(
+                    "delete_note",
+                    {"id": note["id"]},
+                    **common,
+                ),
+                {"ok": True, "id": note["id"]},
+            )
+
+            status = execute_agent_tool(
+                "create_status",
+                {"title": "паспорт", "status": "ожидание"},
+                **common,
+            )
+            self.assertEqual(
+                status,
+                {
+                    "ok": True,
+                    "id": status["id"],
+                    "title": "паспорт",
+                    "status": "ожидание",
+                },
+            )
+            self.assertEqual(
+                execute_agent_tool(
+                    "update_status",
+                    {"id": status["id"], "status": "готово"},
+                    **common,
+                ),
+                {"ok": True, "id": status["id"], "status": "готово"},
+            )
+            self.assertEqual(
+                execute_agent_tool("list_statuses", {}, **common)["items"][0][
+                    "status"
+                ],
+                "готово",
+            )
+            self.assertEqual(
+                execute_agent_tool(
+                    "delete_status",
+                    {"id": status["id"]},
+                    **common,
+                ),
+                {"ok": True, "id": status["id"]},
+            )
+
+    def test_unknown_tool_error_remains_stable(self) -> None:
+        with tempfile.TemporaryDirectory() as directory:
+            result = execute_agent_tool(
+                "missing",
+                {},
+                AssistantStorage(Path(directory) / "assistant.sqlite3"),
+                user_id=42,
+                chat_id=100,
+                tz=ZoneInfo("UTC"),
+            )
+
+        self.assertEqual(
+            result,
+            {"ok": False, "error": "unknown tool: missing"},
+        )
+
+
 class StorageTests(unittest.TestCase):
     def test_user_authorization_is_persisted(self) -> None:
         with tempfile.TemporaryDirectory() as directory: