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Prompting Qwen3 (small / coder)

How to prompt Alibaba's smaller Qwen3 models — the dense 4B/8B/14B/32B variants and the coder builds — sized for local and single-GPU use under Apache 2.0. Read the shared Prompting guides principles first; this guide carries only what is distinctive to Qwen3. This is reference for when you run Qwen3 locally, target it, or evaluate it.

When to reach for it

Qwen3 is the versatile open-weight all-rounder, and its coder variants are a strong local coding pick. Reach for a small Qwen3 when you want a permissively-licensed model that runs on consumer hardware, with a hybrid thinking mode you can switch off for cheap, latency-sensitive turns.

Prompting principles

• Switch thinking with the mode toggle. Qwen3 has a hybrid thinking mode: enable_thinking=True (default) for reasoning, and enable_thinking=False — or the soft /no_think tag in the prompt — for a direct answer. Match the sampling to the mode (below), and use /think mid-conversation to re-enable it for a hard turn.
• Set sampling by mode, and never greedy-decode while thinking. Qwen recommends temperature 0.6 / top-p 0.95 in thinking mode and temperature 0.7 / top-p 0.8 in non-thinking mode. Greedy decoding (temp 0) in thinking mode causes repetition and degraded output — avoid it.
• Keep it lean for coder variants. Name the language, framework, and versions and give the exact deliverable; the coder builds respond well to concrete, well-scoped tasks rather than open-ended prose.
• Mind the local context budget. The small variants run in tight VRAM — keep prompts focused and cap output length so a long thinking trace doesn't exhaust the window on-device.