Test-First AI Development

A framework for building reliable AI applications using test-driven development principles and breaking down complex tasks. Based on YC's Gary Tan's insights.

Core Philosophy for AI Development

  • Write test cases before implementing AI functionality
  • Avoid "raw dogging" prompts without proper testing
  • Break down complex tasks into smaller, manageable steps
  • Focus on real customer data and use cases
  • Build worldview directly from customer experiences

Implementation Strategy

  • Start with real business problems

    • Find companies spending significant money on knowledge work
    • Target businesses using offshore teams/call centers
    • Look for repetitive, rote knowledge work tasks
  • Development Process

    • Get access to real customer data flows
    • Watch how current work is done
    • Write test cases based on actual usage
    • Implement with proper evals
    • Validate against real-world scenarios

Technical Guidelines

  • Current LLM Capabilities

    • Models operate at ~120 IQ level work
    • Can handle structured, repetitive tasks well
    • Need careful prompt engineering
  • Task Management

    • Break down complex prompts into smaller steps
    • Use chain of thought reasoning
    • Reduce context window load
    • Don't ask LLMs to do too much at once

Common Pitfalls to Avoid

  • Creating demo-ware just to raise money
  • Writing prompts without proper testing
  • Giving LLMs too complex tasks
  • Not using real customer data for validation
  • Failing to implement proper evals

Future Considerations

  • Expect continued improvements in model capabilities
  • Plan for cost structures to decrease by 10x
  • Focus on establishing brand and moats early
  • Build systems that can scale with improving technology
  • Maintain focus on real customer problems and data
GT

Garry Tan

President & CEO, Y Combinator

Hi, I'm Garry Tan. I live in San Francisco.

Find me on X at https://x.com/garrytan

I am President and CEO of Y Combinator. I was a partner there from 2011 to 2015.

I started a venture capital fund called Initialized Capital. It has just over $3.2B under management, usually funding folks very early (seed and Series A) often when it is just a few people just starting out.