Compare Architectures
Side-by-side: use case, requirements, latency, cost, strengths, weaknesses, failure modes, example — and when to choose each.
Workflow vs AgentSingle agent vs Multi-agentRAG vs Fine-tuningVector search vs BM25Function calling vs MCPDirect API integration vs MCPPlan-then-execute vs ReActShort-term memory vs Long-term memoryLLM-as-judge vs Deterministic evaluatorsHuman-in-the-loop vs Human-on-the-loopSupervisor vs PipelinePrompt caching vs Semantic cachingRouter vs SupervisorFramework vs No framework
| Plan-then-execute | ReAct | |
|---|---|---|
| Use case | Long tasks with dependent steps that can be foreseen | Exploratory tasks where each observation changes the next move |
| Requirements | Planner call, executor loop, replanning trigger | Single loop interleaving thought, action, observation |
| Latency | Upfront planning call, then often fewer total steps | No upfront cost, but can wander through many steps |
| Cost | Extra planning tokens; cheaper when the plan holds | Cheaper on short tasks; expensive when it meanders |
| Strengths | Inspectable plan, parallelizable independent steps, easy approval gate | Adapts immediately to surprises |
| Weaknesses | Plans go stale when early steps fail | No global view; repeats work; hard to insert approvals |
| Failure modes | Executes a stale plan against changed state | Loops on the same action; forgets the goal |
| Example | Migrate 12 config files following a dependency order | Find why a test fails by reading and probing |
| Choose this when | Choose plan-then-execute when steps are dependent and reviewable up front. | Choose ReAct for short, exploratory tasks; add a step budget either way. |