feat(MCPServer): avoid unnecessary notifications when Resource/Tool not exists

Author: cryo-zd

server/resource_test.go

@@ -98,7 +98,7 @@ func TestMCPServer_RemoveResource(t *testing.T) {
 			},
 		},
 		{
-			name: "RemoveResource with non-existent resource does nothing",
+			name: "RemoveResource with non-existent resource does nothing and not receives notifications from MCPServer",
 			action: func(t *testing.T, server *MCPServer, notificationChannel chan mcp.JSONRPCNotification) {
 				// Add a test resource
 				server.AddResource(
@@ -130,10 +130,11 @@ func TestMCPServer_RemoveResource(t *testing.T) {
 				// Remove a non-existent resource
 				server.RemoveResource("test://nonexistent")
 			},
-			expectedNotifications: 1, // Still sends a notification
+			expectedNotifications: 0, // No notifications expected
 			validate: func(t *testing.T, notifications []mcp.JSONRPCNotification, resourcesList mcp.JSONRPCMessage) {
-				// Check that we received a list_changed notification
-				assert.Equal(t, mcp.MethodNotificationResourcesListChanged, notifications[0].Method)
+				// verify that no notifications were sent
+				assert.Empty(t, notifications)
+
 
 				// The original resource should still be there
 				resp, ok := resourcesList.(mcp.JSONRPCResponse)

server/server.go

@@ -336,11 +336,14 @@ func (s *MCPServer) AddResource(
 // RemoveResource removes a resource from the server
 func (s *MCPServer) RemoveResource(uri string) {
 	s.resourcesMu.Lock()
-	delete(s.resources, uri)
+	_, exists := s.resources[uri]
+	if exists {
+		delete(s.resources, uri)
+	}
 	s.resourcesMu.Unlock()
 
-	// Send notification to all initialized sessions if listChanged capability is enabled
-	if s.capabilities.resources != nil && s.capabilities.resources.listChanged {
+	// Send notification to all initialized sessions if listChanged capability is enabled and we actually remove a resource 
+	if exists && s.capabilities.resources != nil && s.capabilities.resources.listChanged {
 		s.SendNotificationToAllClients(mcp.MethodNotificationResourcesListChanged, nil)
 	}
 }
@@ -448,13 +451,17 @@ func (s *MCPServer) SetTools(tools ...ServerTool) {
 // DeleteTools removes a tool from the server
 func (s *MCPServer) DeleteTools(names ...string) {
 	s.toolsMu.Lock()
+	var exists bool
 	for _, name := range names {
-		delete(s.tools, name)
+		if _, ok := s.tools[name]; ok {
+			delete(s.tools, name)
+			exists = true
+		}
 	}
 	s.toolsMu.Unlock()
 
 	// When the list of available tools changes, servers that declared the listChanged capability SHOULD send a notification.
-	if s.capabilities.tools.listChanged {
+	if exists && s.capabilities.tools != nil && s.capabilities.tools.listChanged {
 		// Send notification to all initialized sessions
 		s.SendNotificationToAllClients(mcp.MethodNotificationToolsListChanged, nil)
 	}

server/server_test.go

@@ -308,6 +308,34 @@ func TestMCPServer_Tools(t *testing.T) {
 				assert.Empty(t, result.Tools, "Expected empty tools list")
 			},
 		},
+		{
+			name: "DeleteTools with non-existent tools does nothing and not receives notifications from MCPServer",
+			action: func(t *testing.T, server *MCPServer, notificationChannel chan mcp.JSONRPCNotification) {
+				err := server.RegisterSession(context.TODO(), &fakeSession{
+					sessionID:           "test",
+					notificationChannel: notificationChannel,
+					initialized:         true,
+				})
+				require.NoError(t, err)
+				server.SetTools(
+					ServerTool{Tool: mcp.NewTool("test-tool-1")},
+					ServerTool{Tool: mcp.NewTool("test-tool-2")})
+
+				// Remove non-existing tools
+				server.DeleteTools("test-tool-3", "test-tool-4")
+			},
+			expectedNotifications: 1,
+			validate: func(t *testing.T, notifications []mcp.JSONRPCNotification, toolsList mcp.JSONRPCMessage) {
+				// Only one notification expected for SetTools
+				assert.Equal(t, mcp.MethodNotificationToolsListChanged, notifications[0].Method)
+
+				// Confirm the tool list does not change
+				tools := toolsList.(mcp.JSONRPCResponse).Result.(mcp.ListToolsResult).Tools
+				assert.Len(t, tools, 2)
+				assert.Equal(t, "test-tool-1", tools[0].Name)
+				assert.Equal(t, "test-tool-2", tools[1].Name)
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {