patronus-lynx.md

Patronus Lynx Integration

NeMo Guardrails supports hallucination detection in RAG systems using Patronus AI's Lynx model. The model is hosted on Hugging Face and comes in both a 70B parameters (see here) and 8B parameters (see here) variant.

There are three components of hallucination that Lynx checks for:

• Information in the bot_message is contained in the relevant_chunks
• There is no extra information in the bot_message that is not in the relevant_chunks
• The bot_message does not contradict any information in the relevant_chunks

Setup

Since Patronus Lynx is fully open source, you can host it however you like. You can find a guide to host Lynx using vLLM here.

Usage

Here is how to configure your bot to use Patronus Lynx to check for RAG hallucinations in your bot output:

1. Add a model of type patronus_lynx in config.yml - the example below uses vLLM to run Lynx:

models:
  ...

  - type: patronus_lynx
    engine: vllm_openai
    parameters:
      openai_api_base: "http://localhost:5000/v1"
      model_name: "PatronusAI/Patronus-Lynx-70B-Instruct" # "PatronusAI/Patronus-Lynx-8B-Instruct"

2. Add the guardrail name is patronus lynx check output hallucination to your output rails in config.yml:

rails:
  output:
    flows:
      - patronus lynx check output hallucination

3. Add a prompt for patronus_lynx_check_output_hallucination in the prompts.yml file:

prompts:
  - task: patronus_lynx_check_output_hallucination
    content: |
      Given the following QUESTION, DOCUMENT and ANSWER you must analyze ...
      ...

We recommend you base your Lynx hallucination detection prompt off of the provided example here.

Under the hood, the patronus lynx check output hallucination rail runs the patronus_lynx_check_output_hallucination action, which you can find here. It returns whether a hallucination is detected (True or False) and potentially a reasoning trace explaining the decision. The bot's response will be blocked if hallucination is True. Note: If Lynx's outputs are misconfigured or a hallucination decision cannot be found, the action default is to return True for hallucination.

Here's the patronus lynx check output hallucination flow, showing how the action is executed:

define bot inform answer unknown
  "I don't know the answer to that."

define flow patronus lynx check output hallucination
  $patronus_lynx_response = execute patronus_lynx_check_output_hallucination
  $hallucination = $patronus_lynx_response["hallucination"]
  # The Reasoning trace is currently unused, but can be used to modify the bot output
  $reasoning = $patronus_lynx_response["reasoning"]

  if $hallucination
    bot inform answer unknown
    stop