building-with-llms▌
refoundai/lenny-skills · updated Apr 8, 2026
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Practical guidance for building effective AI applications using techniques from 60 product leaders and practitioners.
- ›Covers core prompting patterns: few-shot examples, decomposition for complex tasks, self-criticism, and context placement for cache efficiency
- ›Emphasizes architecture decisions over prompt tuning: context engineering, RAG data preparation, layered model supervision, and specialized models for specific tasks
- ›Provides evaluation frameworks: mandatory evals with binary P
Building with LLMs
Help the user build effective AI applications using practical techniques from 60 product leaders and AI practitioners.
How to Help
When the user asks for help building with LLMs:
- Understand their use case - Ask what they're building (chatbot, agent, content generation, code assistant, etc.)
- Diagnose the problem - Help identify if issues are prompt-related, context-related, or model-selection related
- Apply relevant techniques - Share specific prompting patterns, architecture approaches, or evaluation methods
- Challenge common mistakes - Push back on over-reliance on vibes, skipping evals, or using the wrong model for the task
Core Principles
Prompting
Few-shot examples beat descriptions Sander Schulhoff: "If there's one technique I'd recommend, it's few-shot prompting—giving examples of what you want. Instead of describing your writing style, paste a few previous emails and say 'write like this.'"
Provide your point of view Wes Kao: "Sharing my POV makes output way better. Don't just ask 'What would you say?' Tell it: 'I want to say no, but I'd like to preserve the relationship. Here's what I'd ideally do...'"
Use decomposition for complex tasks Sander Schulhoff: "Ask 'What subproblems need solving first?' Get the list, solve each one, then synthesize. Don't ask the model to solve everything at once."
Self-criticism improves output Sander Schulhoff: "Ask the LLM to check and critique its own response, then improve it. Models can catch their own errors when prompted to look."
Roles help style, not accuracy Sander Schulhoff: "Roles like 'Act as a professor' don't help accuracy tasks. But they're great for controlling tone and style in creative work."
Put context at the beginning Sander Schulhoff: "Place long context at the start of your prompt. It gets cached (cheaper), and the model won't forget its task when processing."
Architecture
Context engineering > prompt engineering Bret Taylor: "If a model makes a bad decision, it's usually lack of context. Fix it at the root—feed better data via MCP or RAG."
RAG quality = data prep quality Chip Huyen: "The biggest gains come from data preparation, not vector database choice. Rewrite source data into Q&A format. Add annotations for context humans take for granted."
Layer models for robustness Bret Taylor: "Having AI supervise AI is effective. Layer cognitive steps—one model generates, another reviews. This moves you from 90% to 99% accuracy."
Use specialized models for specialized tasks Amjad Masad: "We use Claude Sonnet for coding, other models for critiquing. A 'society of models' with different roles outperforms one general model."
200ms is the latency threshold Ryan J. Salva (GitHub Copilot): "The sweet spot for real-time suggestions is ~200ms. Slower feels like an interruption. Design your architecture around this constraint."
Evaluation
Evals are mandatory, not optional Kevin Weil (OpenAI): "Writing evals is becoming a core product skill. A 60% reliable model needs different UX than 95% or 99.5%. You can't design without knowing your accuracy."
Binary scores > Likert scales Hamel Husain: "Force Pass/Fail, not 1-5 scores. Scales produce meaningless averages like '3.7'. Binary forces real decisions."
Start with vibes, evolve to evals Howie Liu: "For novel products, start with open-ended vibes testing. Only move to formal evals once use cases converge."
Validate your LLM judge Hamel Husain: "If using LLM-as-judge, you must eval the eval. Measure agreement with human experts. Iterate until it aligns."
Building & Iteration
Retry failures—models are stochastic Benjamin Mann (Anthropic): "If it fails, try the exact same prompt again. Success rates are much higher on retry than on banging on a broken approach."
Be ambitious in your asks Benjamin Mann: "The difference between effective and ineffective Claude Code users: ambitious requests. Ask for the big change, not incremental tweaks."
Cross-pollinate between models Guillermo Rauch: "When stuck after 100+ iterations, copy the code to a different model (e.g., from v0 to ChatGPT o1). Fresh perspective unblocks you."
Compounding engineering Dan Shipper: "For every unit of work, make the next unit easier. Save prompts that work. Build a library. Your team's AI effectiveness compounds."
Working with AI Tools
Learn to read and debug, not memorize syntax Amjad Masad: "The ROI on coding doubles every 6 months because AI amplifies it. Focus on reading code and debugging—syntax is handled."
Use chat mode to understand Anton Osika: "Use 'chat mode' to ask the AI to explain its logic. 'Why did you do this? What am I missing?' Treat it as a tutor."
Vibe coding is a real skill Elena Verna: "I put vibe coding on my resume. Build functional prototypes with natural language before handing to engineering."
Questions to Help Users
- "What are you building and what's the core user problem?"
- "What does the model get wrong most often?"
- "Are you measuring success systematically or going on vibes?"
- "What context does the model have access to?"
- "Have you tried few-shot examples?"
- "What happens when you retry failed prompts?"
Common Mistakes to Flag
- Vibes forever - Eventually you need real evals, not just "it feels good"
- Prompt-only thinking - Often the fix is better context, not better prompts
- One model for everything - Different models excel at different tasks
- Giving up after one failure - Stochastic systems need retries
- Skipping the human review - AI output needs human validation, especially early on
Deep Dive
For all 110 insights from 60 guests, see references/guest-insights.md
Related Skills
- AI Product Strategy
- AI Evals
- Vibe Coding
- Evaluating New Technology
How to use building-with-llms on Cursor
AI-first code editor with Composer
Prerequisites
Before installing skills in Cursor, ensure your development environment meets these requirements:
- ›Cursor installed and configured on your development machine
- ›Node.js version 16.0+ with npm package manager (verify with
node --version) - ›Active project directory or workspace where you want to add building-with-llms
Execute installation command
Execute the skills CLI command in your project's root directory to begin installation:
The skills CLI fetches building-with-llms from GitHub repository refoundai/lenny-skills and configures it for Cursor.
Select Cursor when prompted
The CLI will show a list of available agents. Use arrow keys to navigate and space to select Cursor:
Verify installation
Confirm successful installation by checking the skill directory location:
Reload or restart Cursor to activate building-with-llms. Access the skill through slash commands (e.g., /building-with-llms) or your agent's skill management interface.
Security & Verification Notice
We perform automated surface-level scans (Gen AI Scanner, Socket, Snyk) during installation. These checks detect common vulnerabilities but do not guarantee complete security. Always review skill source code and verify the publisher's reputation before production use.
Skills execute code in your development environment. Always verify the publisher's identity, review recent commits, and test in isolated environments before production deployment.
List & Monetize Your Skill
Submit your Claude Code skill and start earning
Use Cases▌
Task Automation & Efficiency
Automate repetitive workflows and reduce manual effort
Example
Generate reports, summarize documents, draft communications
Save 3-5 hours per week on routine tasks
Knowledge Enhancement
Learn new skills, understand complex topics, get expert guidance
Example
Explain concepts, provide examples, suggest learning resources
Accelerate learning and skill development by 2x
Quality Improvement
Enhance output quality through reviews, suggestions, and refinements
Example
Review drafts, suggest improvements, catch errors
Improve work quality by 30-40% with less effort
Implementation Guide▌
Prerequisites
- ›Claude Desktop or compatible AI client with skill support
- ›Clear understanding of task or problem to solve
- ›Willingness to iterate and refine outputs
Time Estimate
15-45 minutes depending on use case complexity
Installation Steps
- 1.Install skill using provided installation command
- 2.Test with simple use case relevant to your work
- 3.Evaluate output quality and relevance
- 4.Iterate on prompts to improve results
- 5.Integrate into regular workflow if valuable
Common Pitfalls
- ⚠Expecting perfect results without iteration
- ⚠Not providing enough context in prompts
- ⚠Using skill for tasks outside its intended scope
- ⚠Accepting outputs without review and validation
Best Practices▌
✓ Do
- +Start with clear, specific prompts
- +Provide relevant context and constraints
- +Review and refine all outputs before using
- +Iterate to improve output quality
- +Document successful prompt patterns
✗ Don't
- −Don't use without understanding skill limitations
- −Don't skip validation of outputs
- −Don't share sensitive information in prompts
- −Don't expect skill to replace human judgment
💡 Pro Tips
- ★Be specific about desired format and style
- ★Ask for multiple options to choose from
- ★Request explanations to understand reasoning
- ★Combine AI efficiency with human expertise
When to Use This▌
✓ Use When
Use when skill capabilities match your task, clear ROI on time saved, and you can validate outputs. Best for repetitive tasks, learning, and quality improvement.
✗ Avoid When
Avoid when task requires deep expertise you can't validate, involves sensitive decisions, or when learning process is more valuable than speed of completion.
Learning Path▌
- 1Familiarize yourself with skill capabilities and limitations
- 2Start with low-risk, non-critical tasks
- 3Progress to more complex and valuable use cases
- 4Build expertise through regular use and experimentation
Discussion
Product Hunt–style comments (not star reviews)- No comments yet — start the thread.
Ratings
4.7★★★★★73 reviews- ★★★★★Benjamin Chen· Dec 28, 2024
Useful defaults in building-with-llms — fewer surprises than typical one-off scripts, and it plays nicely with `npx skills` flows.
- ★★★★★Kiara Malhotra· Dec 20, 2024
building-with-llms has been reliable in day-to-day use. Documentation quality is above average for community skills.
- ★★★★★Ganesh Mohane· Dec 12, 2024
We added building-with-llms from the explainx registry; install was straightforward and the SKILL.md answered most questions upfront.
- ★★★★★Shikha Mishra· Dec 8, 2024
I recommend building-with-llms for anyone iterating fast on agent tooling; clear intent and a small, reviewable surface area.
- ★★★★★Benjamin Yang· Dec 4, 2024
building-with-llms is among the better-maintained entries we tried; worth keeping pinned for repeat workflows.
- ★★★★★Kiara Gupta· Nov 27, 2024
building-with-llms reduced setup friction for our internal harness; good balance of opinion and flexibility.
- ★★★★★Anaya Robinson· Nov 23, 2024
I recommend building-with-llms for anyone iterating fast on agent tooling; clear intent and a small, reviewable surface area.
- ★★★★★Kwame Kapoor· Nov 23, 2024
Keeps context tight: building-with-llms is the kind of skill you can hand to a new teammate without a long onboarding doc.
- ★★★★★Hana Park· Nov 19, 2024
building-with-llms has been reliable in day-to-day use. Documentation quality is above average for community skills.
- ★★★★★Lucas Anderson· Nov 19, 2024
I recommend building-with-llms for anyone iterating fast on agent tooling; clear intent and a small, reviewable surface area.
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