Anthropic's five workflow patterns (Dec 2024)
1. prompt chaining — sequential, optional programmatic gate
LLM A
gate: pass?
LLM B
LLM C
output
use when: task has clean linear decomposition
2. routing — classifier dispatches to specialist handlers
classifier LLM
refund chain
bug chain
sales chain
use when: categorically different inputs need different handling
3. parallelization — sectioning or voting
LLM 1
LLM 2
LLM 3
aggregate
voting: majority / synthesis
4. orchestrator-workers — dynamic dispatch
orchestrator
worker A
worker B
synth
like agent but orchestrator does not loop indefinitely
5. evaluator-optimizer — propose, judge, refine
proposer LLM
evaluator LLM
pass output
fail feedback loops to proposer
Self-Refine (Lesson 05) generalized; CRITIC pattern if evaluator grounds on external tools
five patterns cover most use cases. agents only when steps cannot be predicted.