Agents vs Simple LLM Apps

Understand the key differences between simple LLM applications and autonomous AI agents

Practical Application

Now you understand the differences. But when should you actually choose each approach? Let's build a decision framework.

The Decision Matrix

Use Simple LLM When...

  • Task is well-defined: "Summarize this text," "Translate to Spanish," "Generate product description"
  • Single-step execution: Input → Output, no iteration needed
  • Speed is critical: Need sub-second response times (<500ms)
  • Cost is a constraint: Budget is $0.001-0.01 per request
  • No external data needed: Answer can be generated from model knowledge
  • Predictability matters: Same input should give similar output every time
EXAMPLE USE CASES
• Content generation (blog posts, emails)
• Text classification (sentiment, categories)
• Code completion (autocomplete, snippets)
• Translation & summarization

🤖Use Agent When...

  • Task requires exploration: "Find the cheapest flight," "Diagnose this bug," "Research this topic"
  • Multi-step reasoning: Plan → Act → Observe → Adjust loop needed
  • External tools required: APIs, databases, file systems, browsers
  • Latency is acceptable: Users can wait 5-30 seconds for thorough results
  • High-value tasks: ROI justifies 5-20x cost increase
  • Autonomy adds value: User wants to "set and forget"
EXAMPLE USE CASES
• Customer support automation
• Data analysis & research
• Software debugging & testing
• Booking & scheduling

Interactive Decision Framework

Answer these questions about your use case, and we'll recommend the best approach:

1. Does your task require external tools or APIs?

2. Can the task be completed in a single response?

3. What's your latency requirement?

4. What's the value of automation?

Real-World Case Studies

📝

Grammarly: LLM for Speed

Real-time writing assistant needs <100ms latency. Uses fine-tuned LLMs for grammar/style suggestions.

Why not agent? Speed is non-negotiable. Single-pass corrections sufficient.
🤖

Intercom Fin: Agent for Autonomy

Customer support agent searches knowledge base, checks order status, processes refunds autonomously. 50% ticket resolution rate.

Why agent? Multi-step workflows, tool use, decision-making required.
🔀

GitHub Copilot: Hybrid Approach

Code completion uses LLM (fast). Workspace feature uses agent (codebase analysis, multi-file edits).

Why hybrid? Different features have different requirements.