diff --git a/backend/tests/services/mcp/test_routing.py b/backend/tests/services/mcp/test_routing.py
index a039637..3737c02 100644
--- a/backend/tests/services/mcp/test_routing.py
+++ b/backend/tests/services/mcp/test_routing.py
@@ -2,15 +2,13 @@
 Tests for MCP Tool Call Routing
 """
 
-from unittest.mock import AsyncMock, MagicMock, patch
+from unittest.mock import AsyncMock, patch
 
 import pytest
 
 from app.services.mcp.config import MCPConfig, MCPServerConfig
 from app.services.mcp.connection import ConnectionPool
 from app.services.mcp.exceptions import (
-    MCPCircuitOpenError,
-    MCPToolError,
     MCPToolNotFoundError,
 )
 from app.services.mcp.registry import MCPServerRegistry
@@ -79,7 +77,10 @@ class TestToolInfo:
             name="create_issue",
             description="Create a new issue",
             server_name="issues",
-            input_schema={"type": "object", "properties": {"title": {"type": "string"}}},
+            input_schema={
+                "type": "object",
+                "properties": {"title": {"type": "string"}},
+            },
         )
         assert info.name == "create_issue"
         assert info.description == "Create a new issue"
@@ -174,9 +175,7 @@ class TestToolRouter:
 
         # Mock the pool connection and request
         mock_conn = AsyncMock()
-        mock_conn.execute_request = AsyncMock(
-            return_value={"result": {"status": "ok"}}
-        )
+        mock_conn.execute_request = AsyncMock(return_value={"result": {"status": "ok"}})
         mock_conn.is_connected = True
 
         with patch.object(router._pool, "get_connection", return_value=mock_conn):
@@ -232,9 +231,7 @@ class TestToolRouter:
         await router.register_tool_mapping("tool-on-server-1", "server-1")
 
         mock_conn = AsyncMock()
-        mock_conn.execute_request = AsyncMock(
-            return_value={"result": "routed"}
-        )
+        mock_conn.execute_request = AsyncMock(return_value={"result": "routed"})
         mock_conn.is_connected = True
 
         with patch.object(router._pool, "get_connection", return_value=mock_conn):
@@ -339,7 +336,11 @@ class TestToolRouter:
         delay2 = router._calculate_retry_delay(2, config)
         delay3 = router._calculate_retry_delay(3, config)
 
-        # Delays should increase with attempts
+        # All delays should be positive
         assert delay1 > 0
-        # Allow for jitter variation
+        assert delay2 > 0
+        assert delay3 > 0
+        # All delays should be within max bounds (allow for jitter variation)
         assert delay1 <= config.retry_max_delay * 1.25
+        assert delay2 <= config.retry_max_delay * 1.25
+        assert delay3 <= config.retry_max_delay * 1.25