> ## Documentation Index
> Fetch the complete documentation index at: https://narev.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Import LangSmith traces into a Narev benchmark

> Pull production LangChain traces from LangSmith into a Narev benchmark so you can evaluate new LLM variants against your real production prompts.

<Tip>
  Use your production traces as test datasets. Instead of guessing which model works better, test against the prompts
  your users are actually sending.
</Tip>

## Prerequisites

* An active LangSmith account with production traces
* LangSmith API key (starts with `lsv2*pt*<token>`)
* Production traces in your LangSmith project

## Setup

1. Create a new **A/B test**
2. Navigate to **Setup** tab
3. In the **Data Source** section select **Import from traces**
4. Select **LangSmith** as provider
5. Enter your credentials:
   * **Project Name**: Your LangSmith project identifier
   * **API Key**: Your LangSmith API key (starts with `lsv2*pt*<token>`)
6. Select your **Date Range** (default: last 7 days)
7. Click **Save Project** to import traces

<Frame>
  <img src="https://mintcdn.com/narev/Y1illty3WLN-yruS/images/benchmark/integration/langsmith.webp?fit=max&auto=format&n=Y1illty3WLN-yruS&q=85&s=e9ce19ef6679e1de38bc5883762c7ebd" alt="Import traces from LangSmith interface" width="1574" height="1296" data-path="images/benchmark/integration/langsmith.webp" />
</Frame>

## Common questions

<AccordionGroup>
  <Accordion title="Do I need to modify my LangSmith setup?">
    No. Narev reads from your existing LangSmith project without any changes to your instrumentation.
  </Accordion>

  <Accordion title="Can I test models not in my current LangSmith traces?">
    Yes. Narev imports prompts and usage patterns from LangSmith, then lets you test any supported model provider on
    those same prompts.
  </Accordion>

  <Accordion title="Will Narev send data back to LangSmith?">
    No. Narev imports traces to run experiments but doesn't write back to LangSmith.
  </Accordion>

  <Accordion title="Does Narev work with LangChain and LangGraph?">
    Yes. Narev imports all types of LangSmith runs including LangChain chains, LangGraph agents, and individual LLM
    calls.
  </Accordion>

  <Accordion title="How many traces should I import?">
    For most use cases, 50-500 traces provide statistically significant results. Start with 7 days of data by default.
    For high-variability workloads, import 30 days to capture edge cases.
  </Accordion>
</AccordionGroup>