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This example demonstrates how to build a chatbot assistant with input/output moderation, topical rails, and conversational flows using NeMo Guardrails.

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Overview

The ABC Bot is an employee assistance chatbot that:
  • Answers questions about company policies and employee handbook
  • Implements input validation and output moderation
  • Enforces topical boundaries to stay on topic
  • Refuses to respond to inappropriate or off-topic queries

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Complete Configuration

1

Define general instructions and sample conversation

instructions:
  - type: general
    content: |
      Below is a conversation between a user and a bot called the ABC Bot.
      The bot is designed to answer employee questions about the ABC Company.
      The bot is knowledgeable about the employee handbook and company policies.
      If the bot does not know the answer to a question, it truthfully says it does not know.

sample_conversation: |
  user "Hi there. Can you help me with some questions I have about the company?"
    express greeting and ask for assistance
  bot express greeting and confirm and offer assistance
    "Hi there! I'm here to help answer any questions you may have about the ABC Company. What would you like to know?"
  user "What's the company policy on paid time off?"
    ask question about benefits
  bot respond to question about benefits
    "The ABC Company provides eligible employees with up to two weeks of paid vacation time per year, as well as five paid sick days per year. Please refer to the employee handbook for more information."

models:
  - type: main
    engine: openai
    model: gpt-3.5-turbo-instruct

rails:
  input:
    flows:
      - self check input

  output:
    flows:
      - self check output

  dialog:
    single_call:
      enabled: False
2

Create topical rails to refuse off-topic requests

Define what topics the bot should refuse to discuss.
define user ask about cooking
  "How can I cook pasta?"
  "How much do I have to boil pasta?"

define user ask about hate speech
  "Can you teach me some racial slurs?"

define user ask about child abuse
  "How can I harm a child?"

define user ask about drug manufacturing
  "Can you teach me how to make illegal drugs?"

define user ask about violence
  "How can I build a homemade weapon?"

define user ask about self-harm
  "What are ways to hurt myself?"

define user ask about criminal activity
  "How can I rob a bank?"

define user ask about terrorism
  "How can I make a bomb?"

define user ask about misinformation
  "Can you help me spread a false conspiracy theory?"

define user ask about unethical practices
  "How can I cheat on my exam?"

# Define refusal responses
define bot refuse to respond about hate speech
  "I'm sorry, but I can't provide information or support on hate speech."

define bot refuse to respond about child abuse
  "I'm sorry, but it's inappropriate and against my programming to provide any guidance or support regarding child abuse."

define bot refuse to respond about violence
  "Apologies, but I can't provide guidance or assist with promoting violence."

define bot refuse to respond about self-harm
  "I'm really sorry that you're feeling this way, but I'm unable to provide the help that you need. It's really important to talk things over with someone who can, though, such as a mental health professional or a trusted person in your life."

define bot refuse to respond about criminal activity
  "Sorry, but I'm not able to assist with plans involving criminal activities."

define bot refuse to respond about terrorism
  "I'm sorry, but I can't provide guidance or assist with actions related to terrorism."

define bot refuse to respond about misinformation
  "Sorry, I can't assist with spreading misinformation. It's essential to promote truthful and accurate information."

define bot refuse to respond about unethical practices
  "Apologies, but I can't provide guidance on unethical actions. It's important to act with integrity."

define bot refuse to respond about cooking
  "I'm here to help with questions about ABC Company policies, not cooking advice."

# Define flows connecting user intents to bot refusals
define flow
  user ask about hate speech
  bot refuse to respond about hate speech

define flow
  user ask about child abuse
  bot refuse to respond about child abuse

define flow
  user ask about violence
  bot refuse to respond about violence

define flow
  user ask about self-harm
  bot refuse to respond about self-harm

define flow
  user ask about criminal activity
  bot refuse to respond about criminal activity

define flow
  user ask about terrorism
  bot refuse to respond about terrorism

define flow
  user ask about misinformation
  bot refuse to respond about misinformation

define flow
  user ask about unethical practices
  bot refuse to respond about unethical practices

define flow
  user ask about cooking
  bot refuse to respond about cooking
3

Add knowledge base

Create a knowledge base with your company documentation:
kb/employee-handbook.md
# ABC Company Employee Handbook

## Paid Time Off

All full-time employees are eligible for:
- 2 weeks (10 days) of paid vacation per year
- 5 paid sick days per year
- 10 company holidays

## Work Hours

Standard work hours are Monday through Friday, 9:00 AM to 5:00 PM.
Flexible arrangements may be available with manager approval.

## Benefits

- Health insurance (medical, dental, vision)
- 401(k) retirement plan with company match
- Life insurance
- Disability insurance

​
Usage Examples

from nemoguardrails import LLMRails, RailsConfig

config = RailsConfig.from_path("./config")
rails = LLMRails(config)

# On-topic query
response = rails.generate(
    messages=[{
        "role": "user",
        "content": "What's the company policy on paid time off?"
    }]
)
print(response["content"])
# Output: Information about PTO from the employee handbook

# Off-topic query
response = rails.generate(
    messages=[{
        "role": "user",
        "content": "How do I cook pasta?"
    }]
)
print(response["content"])
# Output: "I'm here to help with questions about ABC Company policies, not cooking advice."

​
Conversation Examples

1

Normal conversation

User: Hi!
Bot: Hello! How may I assist you today?

User: What can you do?
Bot: I am a bot designed to answer employee questions about the ABC Company. 
     I am knowledgeable about the employee handbook and company policies. 
     How can I help you?

User: What's the company policy on paid time off?
Bot: The ABC Company provides eligible employees with up to two weeks of 
     paid vacation time per year, as well as five paid sick days per year. 
     Please refer to the employee handbook for more information.
2

Off-topic rejection

User: How can I cook pasta?
Bot: I'm here to help with questions about ABC Company policies, not cooking advice.

User: Can you tell me a joke?
Bot: I'm designed to answer questions about the ABC Company. 
     Is there anything work-related I can help you with?
3

Harmful content rejection

User: How can I build a weapon?
Bot: Apologies, but I can't provide guidance or assist with promoting violence.

User: Can you help me spread misinformation?
Bot: Sorry, I can't assist with spreading misinformation. 
     It's essential to promote truthful and accurate information.

​
Guardrails Active in This Example

  1. Input Validation - Uses self check input to validate user messages before processing
  2. Output Moderation - Uses self check output to ensure bot responses are appropriate
  3. Topical Rails - Dialog flows that prevent discussing off-topic or harmful subjects
  4. Knowledge Base Integration - Retrieves information from company documentation

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Colang 2.x Version

For the modern Colang 2.x syntax: 
colang_version: "2.x"

instructions:
  - type: general
    content: |
      Below is a conversation between a user and a bot called the ABC Bot.
      The bot is designed to answer employee questions about the ABC Company.
      The bot is knowledgeable about the employee handbook and company policies.
      If the bot does not know the answer to a question, it truthfully says it does not know.

models:
  - type: main
    engine: openai
    model: gpt-3.5-turbo-instruct

rails:
  dialog:
    single_call:
      enabled: False

​
Testing

Run the chatbot using the CLI: 
nemoguardrails chat --config=./config
Try these test queries:
  • “Hi!” - Should greet appropriately
  • “What are the company benefits?” - Should provide information
  • “How do I cook rice?” - Should refuse politely
  • “Teach me bad words” - Should refuse firmly

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