promptfoo/.cursor/rules/examples.mdc

---
description: This rule provides guidance for creating and maintaining examples in the promptfoo project, which has an extensive collection of example configurations.
globs: examples/**/*
alwaysApply: false
---

# Examples Development Guidelines

## Example Structure

- Each example should have its own directory with a clear, descriptive name
- The README.md must begin with the folder name as an H1 heading:
  ```markdown
  # example-name (human readable name)
  ```
- Every example README must include how to run it with:

  ````markdown
  You can run this example with:

  ```bash
  npx promptfoo@latest init --example example-name
  ```
  ````

- Include a comprehensive README.md that explains:
  - The purpose of the example
  - Required prerequisites or setup
  - Step-by-step instructions for running the example
  - Expected outputs or results
- Structure examples consistently with common patterns across the project
- Include a working `promptfooconfig.yaml` (or equivalent) file

## Configuration File Structure

- Always include the YAML schema reference at the top of configuration files:
  ```yaml
  # yaml-language-server: $schema=https://promptfoo.dev/config-schema.json
  ```
- Follow this specific field order in all configuration files:
  1. `description` - A SHORT clear description of what the example demonstrates. Between 3 and 10 words
  2. `env` (optional) - Environment variable settings. Only define if absolutely necessary
  3. `prompts` - The prompts to evaluate
  4. `providers` - The models/providers to test
  5. `defaultTest` (optional) - Default assertions for all tests
  6. `scenarios` (optional) - Named test scenarios
  7. `tests` - Test cases with variables and assertions
- Ensure all configuration files pass YAML lint validation
- When referencing external files, always use the `file://` prefix:
  ```yaml
  prompts:
    - file://prompts/system_message.txt
  ```
- For trivial test cases, make them quirky and fun to increase engagement

## Model Selection

- Always use the latest model versions available in 2025
- For OpenAI, prefer models like:
  - `openai:o3-mini`
  - `openai:gpt-4o-mini`
- For Anthropic, prefer models like:
  - `anthropic:claude-3-7-sonnet-20250219`
- For open-source models, use the latest versions available:
  - Latest Llama
- Include a mix of providers when comparing model performance
- Document any model-specific capabilities or limitations in examples
- When demonstrating specialized capabilities (vision, audio, etc.), use models that support those features

## Environment Variables

- Clearly list all required environment variables at the beginning of the README
- For each environment variable, explain:
  - Its purpose
  - How to obtain it (for API keys)
  - Any default values or constraints
- Include a sample `.env` file or instructions when multiple variables are needed:

  ```markdown
  ## Environment Variables

  This example requires the following environment variables:

  - `OPENAI_API_KEY` - Your OpenAI API key
  - `ANTHROPIC_API_KEY` - Your Anthropic API key

  You can set these in a `.env` file or directly in your environment.
  ```

## Example Quality

- Ensure all examples are functional and up-to-date
- Keep examples as simple as possible while still demonstrating the concept
- Examples should work with publicly available APIs when possible
- Document any required API keys or credentials
- Include placeholder values for secrets/credentials
- Provide instructions for cleaning up resources after running the example

## Configuration Examples

### Basic Example

```yaml
# yaml-language-server: $schema=https://promptfoo.dev/config-schema.json
description: A simple evaluation of translation quality
prompts:
  - Translate "{{input}}" to {{language}}
providers:
  - openai:o3-mini
  - anthropic:claude-3-7-sonnet-latest
tests:
  - vars:
      input: Hello, world!
      language: French
    assert:
      - type: contains
        value: Bonjour
  - vars:
      input: How are you today?
      language: German
    assert:
      - type: contains
        value: heute
```

### Example with Optional Fields

```yaml
# yaml-language-server: $schema=https://promptfoo.dev/config-schema.json
description: Evaluating joke quality across different models
env:
  TEMPERATURE: 0.7
prompts:
  - file://prompts/joke_prompt.txt
providers:
  - id: gpt-5-creative
    provider: openai:gpt-5-preview
    temperature: $TEMPERATURE
  - anthropic:claude-3-7-sonnet-latest
defaultTest:
  assert:
    - type: javascript
      value: return output.length > 20 ? 'pass' : 'fail'
scenarios:
  funny-animals:
    vars:
      topic: animals
      style: slapstick
tests:
  - vars:
      topic: computers
      style: dad joke
    assert:
      - type: llm-rubric
        value: Rate this joke on a scale of 1-10 for humor
```

## Code Style

- Follow the same code style guidelines as the main project
- Include comments to explain non-obvious parts
- Use descriptive variable and function names
- Format configuration files consistently
- Keep code DRY within reason (examples may duplicate code for clarity)

## Provider Examples

- When creating examples for specific providers:
  - Explain any provider-specific configuration
  - Document required environment variables
  - Include information about pricing or usage limits
  - Highlight unique features or capabilities
  - Compare to similar providers where appropriate
  - Always use the latest available model versions for that provider

## Maintenance

- Review examples periodically to ensure they still work
- Update examples when APIs or dependencies change
- Remove outdated examples or mark them as deprecated
- Test examples as part of the CI process when feasible
- Keep dependencies updated in example requirements files
- Update model versions when new ones become available

## Documentation Integration

- Reference examples in relevant documentation
- Make it clear which features each example demonstrates
- Group related examples together
- Include links to more comprehensive documentation where appropriate
- Consider creating guides that walk through multiple examples

```

```