diff --git a/public/css/toggle-dependent.css b/public/css/toggle-dependent.css
index 9ffc382cc..08bb08fe0 100644
--- a/public/css/toggle-dependent.css
+++ b/public/css/toggle-dependent.css
@@ -463,3 +463,14 @@ body.expandMessageActions .mes .mes_buttons .extraMesButtonsHint {
 label[for="trim_spaces"]:has(input:checked) i.warning {
     display: none;
 }
+
+#claude_function_prefill_warning {
+    display: none;
+}
+
+#openai_settings:has(#openai_function_calling:checked):has(#claude_assistant_prefill:not(:placeholder-shown), #claude_assistant_impersonation:not(:placeholder-shown)) #claude_function_prefill_warning {
+    display: flex;
+    align-items: center;
+    gap: 5px;
+    margin: 10px 0;
+}
diff --git a/public/index.html b/public/index.html
index 132d4d4bf..8d48af979 100644
--- a/public/index.html
+++ b/public/index.html
@@ -1873,6 +1873,10 @@
                                             </div>
                                             <textarea id="claude_assistant_impersonation" class="text_pole textarea_compact autoSetHeight" name="assistant_impersonation" rows="2" data-i18n="[placeholder]Start Claude's answer with..." placeholder="Start Claude's answer with..."></textarea>
                                         </div>
+                                        <div id="claude_function_prefill_warning">
+                                            <i class="fa-solid fa-circle-info"></i>
+                                            <span>Prefills won't work when function calling is enabled and any tools are registered.</span>
+                                        </div>
                                         <label for="claude_use_sysprompt" class="checkbox_label widthFreeExpand">
                                             <input id="claude_use_sysprompt" type="checkbox" />
                                             <span data-i18n="Use system prompt (Claude 2.1+ only)">