diff --git a/src/renderer/src/hooks/useAssistant.ts b/src/renderer/src/hooks/useAssistant.ts
index b7edd5ad59..99d26b742c 100644
--- a/src/renderer/src/hooks/useAssistant.ts
+++ b/src/renderer/src/hooks/useAssistant.ts
@@ -43,9 +43,14 @@ export function useAssistant(id: string) {
   const dispatch = useAppDispatch()
   const { defaultModel } = useDefaultModel()
 
+  const model = assistant?.model ?? assistant?.defaultModel ?? defaultModel
+  if (!model) {
+    throw new Error(`Assistant model is not set for assistant with name: ${assistant?.name ?? 'unknown'}`)
+  }
+
   return {
-    assistant,
-    model: assistant?.model ?? assistant?.defaultModel ?? defaultModel,
+    assistant: { ...assistant, model },
+    model,
     addTopic: (topic: Topic) => dispatch(addTopic({ assistantId: assistant.id, topic })),
     removeTopic: (topic: Topic) => {
       TopicManager.removeTopic(topic.id)
diff --git a/src/renderer/src/services/ApiService.ts b/src/renderer/src/services/ApiService.ts
index 65825ee597..2bc1b0ba7c 100644
--- a/src/renderer/src/services/ApiService.ts
+++ b/src/renderer/src/services/ApiService.ts
@@ -247,6 +247,9 @@ export async function fetchChatCompletion({
   console.log('[DEBUG] Got assistant provider:', provider.id)
   const AI = new AiProvider(provider)
 
+  // Make sure that 'Clear Context' works for all scenarios including external tool and normal chat.
+  messages = filterContextMessages(messages)
+
   const lastUserMessage = findLast(messages, (m) => m.role === 'user')
   const lastAnswer = findLast(messages, (m) => m.role === 'assistant')
   if (!lastUserMessage) {
@@ -258,7 +261,7 @@ export async function fetchChatCompletion({
   // They will be retrieved and used by the messageThunk later to create CitationBlocks.
   const { mcpTools } = await fetchExternalTool(lastUserMessage, assistant, onChunkReceived, lastAnswer)
 
-  const filteredMessages = filterUsefulMessages(filterContextMessages(messages))
+  const filteredMessages = filterUsefulMessages(messages)
 
   // --- Call AI Completions ---
   console.log('[DEBUG] Calling AI.completions')