Zero-Shot Prompting

Reviewed by Proof · Updated

Definition

Zero-shot prompting means asking a model to do a task with instructions only, without giving it any examples.

Key takeaways

  • You describe the task and the model does it, with no sample answers.
  • It's the simplest prompt and the cheapest in input tokens.
  • It works well for common tasks like summarizing, translating and answering questions.
  • If the output format drifts or labels are inconsistent, add examples. See Few-Shot Prompting.

When it's enough

Modern chat models are trained to follow instructions, so many tasks need nothing more than a clear request. Zero-shot is a good first try because it's quick to write and easy to change.

It works best when:

  • The task is common and well defined.
  • You spell out the output format in words ("Reply with one word", "Use a bulleted list").
  • There's little room for different reasonable answers.

When to add more

Move to few-shot prompting or stricter formats when:

  • The model uses slightly different labels or wording each time.
  • The task uses your own categories or style that it can't guess.
  • You need machine-readable output. See JSON Mode.

Example

curl https://api.luv13.ai/v1/chat/completions \
  -H "Authorization: Bearer $LUV13_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "luv13/glm-5.3-flash",
    "messages": [
      {"role": "user", "content": "Translate to Spanish. Reply with the translation only: Where is the train station?"}
    ]
  }'