From cd9388ac71fb989c3a590668fb3542f5b85a8fdb Mon Sep 17 00:00:00 2001
From: Abdullah <abdullah.basim99@gmail.com>
Date: Mon, 6 Apr 2026 09:59:22 +0300
Subject: [PATCH] fix(chat): support tool_choice in Qwen3.5-VL chat handler

- 'none': tools are not injected into the prompt
- 'required': model is instructed to always call a tool
- 'auto'/None: model follows each tool's description to decide

Fixes: tools were always injected regardless of tool_choice value
---
 llama_cpp/llama_chat_format.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/llama_cpp/llama_chat_format.py b/llama_cpp/llama_chat_format.py
index 3c426b38f..029f53d15 100644
--- a/llama_cpp/llama_chat_format.py
+++ b/llama_cpp/llama_chat_format.py
@@ -5371,7 +5371,7 @@ class Qwen35ChatHandler(MTMDChatHandler):
         "{%- if not messages -%}"
         "    {{- raise_exception('No messages provided.') -}}"
         "{%- endif -%}"
-        "{%- if tools and tools is iterable and tools is not mapping -%}"
+        "{%- if tools and tools is iterable and tools is not mapping and tool_choice != 'none' -%}"
         "    {{- '<|im_start|>system\n' -}}"
         "    {{- '# Tools\n\nYou have access to the following functions:\n\n<tools>' -}}"
         "    {%- for tool in tools -%}"
@@ -5379,6 +5379,11 @@ class Qwen35ChatHandler(MTMDChatHandler):
         "        {{- tool | tojson -}}"
         "    {%- endfor -%}"
         "    {{- '\n</tools>' -}}"
+        "    {%- if tool_choice == 'required' -%}"
+        "        {{- '\n\nYou MUST call at least one function in your response. Answering without a function call is not allowed. Select the most appropriate tool based on the user request and its description.\n' -}}"
+        "    {%- else -%}"
+        "         {{- '\n\nYou have access to tools. Use them only when necessary.\nFollow the description of each tool to determine if and when to call it.\nIf no tool is needed, respond directly.\n' -}}"
+        "    {%- endif -%}"
         "    {{- '\n\nIf you choose to call a function ONLY reply in the following format with NO suffix:\n\n<tool_call>\n<function=example_function_name>\n<parameter=example_parameter_1>\nvalue_1\n</parameter>\n<parameter=example_parameter_2>\nThis is the value for the second parameter\nthat can span\nmultiple lines\n</parameter>\n</function>\n</tool_call>\n\n<IMPORTANT>\nReminder:\n- Function calls MUST follow the specified format: an inner <function=...></function> block must be nested within <tool_call></tool_call> XML tags\n- Required parameters MUST be specified\n- You may provide optional reasoning for your function call in natural language BEFORE the function call, but NOT after\n- If there is no function call available, answer the question like normal with your current knowledge and do not tell the user about function calls\n</IMPORTANT>' -}}"
         "    {%- if messages[0].role == 'system' -%}"
         "        {%- set content = render_content(messages[0].content, false, true) | trim -%}"