diff --git a/lib/ruby_llm/active_record/chat_methods.rb b/lib/ruby_llm/active_record/chat_methods.rb
index c29e637e1..7c6c31bda 100644
--- a/lib/ruby_llm/active_record/chat_methods.rb
+++ b/lib/ruby_llm/active_record/chat_methods.rb
@@ -54,19 +54,23 @@ def provider
         model_association&.provider
       end
 
-      def to_llm
+      def to_llm(reset_messages: true)
         model_record = model_association
         @chat ||= (context || RubyLLM).chat(
           model: model_record.model_id,
           provider: model_record.provider.to_sym,
           assume_model_exists: assume_model_exists || false
         )
-        @chat.reset_messages!
 
-        ordered_messages = order_messages_for_llm(messages_association.to_a)
-        ordered_messages.each do |msg|
-          @chat.add_message(msg.to_llm)
+        if reset_messages
+          @chat.reset_messages!
+
+          ordered_messages = order_messages_for_llm(messages_association.to_a)
+          ordered_messages.each do |msg|
+            @chat.add_message(msg.to_llm)
+          end
         end
+
         reapply_runtime_instructions(@chat)
 
         setup_persistence_callbacks
@@ -89,12 +93,12 @@ def with_runtime_instructions(instructions, append: false, replace: nil)
       end
 
       def with_tool(...)
-        to_llm.with_tool(...)
+        to_llm(reset_messages: false).with_tool(...)
         self
       end
 
       def with_tools(...)
-        to_llm.with_tools(...)
+        to_llm(reset_messages: false).with_tools(...)
         self
       end
 
diff --git a/spec/ruby_llm/active_record/acts_as_spec.rb b/spec/ruby_llm/active_record/acts_as_spec.rb
index 0aee18007..7d2ee491a 100644
--- a/spec/ruby_llm/active_record/acts_as_spec.rb
+++ b/spec/ruby_llm/active_record/acts_as_spec.rb
@@ -152,6 +152,70 @@ def execute(expression:)
       result = chat.with_tool(Calculator)
       expect(result).to eq(chat)
     end
+
+    it 'supports dynamically adding tools during tool execution' do
+      # A tool that dynamically registers another tool on the chat when executed.
+      # This simulates the "ToolSearch" pattern where a tool discovers and registers
+      # new tools mid-conversation via chat.with_tool.
+      dynamic_tool = Class.new(RubyLLM::Tool) do
+        description 'Searches for tools and makes them available'
+        param :query, type: :string, desc: 'Search query'
+
+        attr_accessor :chat_ref
+
+        def execute(query:)
+          chat_ref.with_tool(Calculator)
+          "Found calculator tool for: #{query}"
+        end
+      end
+
+      chat = Chat.create!(model: model)
+      tool_instance = dynamic_tool.new
+      tool_instance.chat_ref = chat
+      chat.with_tool(tool_instance)
+
+      llm_chat = chat.instance_variable_get(:@chat)
+      provider = llm_chat.instance_variable_get(:@provider)
+
+      # First response: model calls the dynamic tool search
+      search_tool_call = RubyLLM::ToolCall.new(
+        id: 'call_1',
+        name: tool_instance.name,
+        arguments: { 'query' => 'calculator' }
+      )
+
+      # Capture messages sent to the provider on each complete call to verify
+      # that no extra empty assistant message is inserted between tool_calls
+      # and tool results (the actual bug this test guards against).
+      messages_per_call = []
+      call_count = 0
+      allow(provider).to receive(:complete) do |messages, **_kwargs, &_block|
+        messages_per_call << messages.map { |m| { role: m.role.to_s, content: m.content.to_s } }
+        call_count += 1
+        case call_count
+        when 1
+          RubyLLM::Message.new(
+            role: :assistant, content: '',
+            tool_calls: { search_tool_call.id => search_tool_call }
+          )
+        else
+          RubyLLM::Message.new(
+            role: :assistant, content: 'Found it!'
+          )
+        end
+      end
+
+      response = chat.ask('Find me a calculator')
+      expect(response.content).to eq('Found it!')
+
+      # On the second provider call, verify no stray empty assistant message
+      # was inserted between the tool_calls assistant and the tool result.
+      # The bug caused messages to be: [user, assistant(tool_calls), assistant(""), tool]
+      # Correct should be: [user, assistant(tool_calls), tool]
+      second_call_roles = messages_per_call[1].map { |m| m[:role] }
+      assistant_count = second_call_roles.count('assistant')
+      expect(assistant_count).to eq(1), "Expected 1 assistant message but got #{assistant_count}: #{second_call_roles}"
+    end
   end
 
   describe 'model switching' do