Building Effective Agents
Anthropic's guide to building agentic LLM systems, advocating for simple composable patterns over complex frameworks.
The most successful agent implementations use simple, composable patterns rather than complex frameworks. Success comes from building the right system for specific needs, not the most sophisticated one.
Agentic Systems Taxonomy
The article distinguishes two categories:
- Workflows: LLMs and tools orchestrated through predefined code paths
- Agents: LLMs dynamically direct their own processes and tool usage
Start with workflows when possible. Move to agents only when you need flexibility at runtime.
Workflow Patterns
Five composable patterns for orchestrating LLMs:
- Prompt Chaining — Sequential decomposition with gates between steps. Each LLM call handles one focused task.
- Routing — Classification directs tasks to specialized handlers. Good for separating distinct request types.
- Parallelization — Run multiple LLM calls concurrently. Use "sectioning" to split work or "voting" for consensus.
- Orchestrator-Workers — Central LLM delegates subtasks dynamically. Useful when work can't be predetermined.
- Evaluator-Optimizer — Iterative refinement loops where one LLM generates and another critiques.
Core Principles
Three principles guide effective agent design:
Simplicity first. Resist adding complexity. Each abstraction layer adds latency and failure modes.
Transparency in planning. Make the agent's reasoning visible. Users need to understand what it's doing and why.
Agent-Computer Interface (ACI). The interface between agent and tools matters as much as the UI between human and software. Invest in clear documentation, error messages, and tool design.
The Building Block
Every agentic system builds on the augmented LLM: a language model enhanced with retrieval, tools, and memory. Get this foundation right before adding orchestration.
Connections
Extends the design patterns covered in agentic-design-patterns. Complements build-autonomous-agents-using-prompt-chaining-with-ai-primitives with Anthropic's production insights. See 12-factor-agents for operational best practices.
Linked References (21)
- AI Agents Guide
- AI codes better than me. Now what?
- AI Expert: We Have 2 Years Before Everything Changes - Tristan Harris
- Andrej Karpathy — We're summoning ghosts, not building animals
- Beads
- Claude Code is a Platform, Not an App
- Context Engineering for AI Agents with LangChain and Manus
- Ex-Google Officer Speaks Out On The Dangers Of AI
- First Impressions of Claude Cowork, Anthropic's General Agent
- How I Use LLMs
- How to Build a Coding Agent: Free Workshop
- How to Build a Coding Agent (Repository)
- RepoMirror
- The Context Window Problem
- The Importance of Agent Harness in 2026
- Thread-Based Engineering: How to Ship Like Boris Cherny
- Understanding Claude Code's Full Stack: MCP, Skills, Subagents, and Hooks Explained
- We Removed 80% of Our Agent's Tools
- Why Prompting Breaks Down and BMAD Doesn't
- You Can't Design Software You Don't Work On
- Zeroshot