ollama - 💡(How to fix) Fix qwen3-vl:8b missing thinking toggle template (think: false ignored) [1 comments, 2 participants]

Description

The qwen3-vl:8b model ships with a bare {{ .Prompt }} template that lacks the $.IsThinkSet / $.Think thinking-control logic present in the qwen3:8b model template. As a result, "think": false in API calls is silently ignored for qwen3-vl:8b, while it works correctly for qwen3:8b.

qwen3-vl:8b template (current)

{{ .Prompt }}

No ChatML structure, no thinking toggle -- just a raw prompt passthrough.

qwen3:8b template (correct)

Full ChatML with $.IsThinkSet, $.Think, /think and /no_think toggle, and proper <think> block handling.

Impact

When using the chat API with "think": false, qwen3-vl:8b ignores the flag entirely. All tokens are consumed by thinking output, producing empty actual responses for any non-trivial prompt.

Example: A 4096 num_predict token budget produces 17,054 characters of thinking and 0 characters of response content.

Steps to Reproduce

1. Confirm the template difference

# qwen3-vl:8b -- bare template
curl -s http://localhost:11434/api/show -d '{"name":"qwen3-vl:8b"}' | jq -r '.template'
# Output: {{ .Prompt }}

# qwen3:8b -- full ChatML template with thinking control
curl -s http://localhost:11434/api/show -d '{"name":"qwen3:8b"}' | jq -r '.template'
# Output: Full template with $.IsThinkSet, $.Think, /no_think logic

2. Send a chat request with think: false

curl -s http://localhost:11434/api/chat -d '{
  "model": "qwen3-vl:8b",
  "messages": [{"role": "user", "content": "What is 2+2? Answer briefly."}],
  "think": false,
  "stream": false,
  "options": {"num_predict": 4096}
}'

Actual result: The response message.content is dominated by <think>...</think> blocks consuming the full token budget. The actual answer is empty or truncated.

Expected result: With "think": false, the model should skip thinking and return a direct response, as qwen3:8b does.

3. Compare with qwen3:8b (works correctly)

curl -s http://localhost:11434/api/chat -d '{
  "model": "qwen3:8b",
  "messages": [{"role": "user", "content": "What is 2+2? Answer briefly."}],
  "think": false,
  "stream": false,
  "options": {"num_predict": 4096}
}'

This correctly returns a direct answer without thinking blocks.

Workaround

Using raw: true with explicit ChatML formatting, appending /no_think to user messages, and prefilling <think>\n\n</think>\n\n in the assistant turn works correctly:

curl -s http://localhost:11434/api/chat -d '{
  "model": "qwen3-vl:8b",
  "messages": [
    {"role": "user", "content": "What is 2+2? Answer briefly. /no_think"},
    {"role": "assistant", "content": "<think>\n\n</think>\n\n"}
  ],
  "raw": true,
  "stream": false,
  "options": {"num_predict": 4096}
}'

Expected Behavior

qwen3-vl:8b should ship with the same ChatML template structure as qwen3:8b, including full $.IsThinkSet / $.Think thinking toggle support. Both models are Qwen3-family and support the same thinking/no-thinking modes.

Version Info

• Ollama 0.16.2 (tested on spark-1)
• Ollama 0.16.3 (tested on spark-2)
• Models: qwen3-vl:8b, qwen3:8b
• OS: Linux (ARM64, DGX Spark)