Guide: Workflow Chaining Patterns — reliable multi-call designs

Many practical assistants require more than a single prompt. Chaining model calls or combining models with tools and retrieval improves reliability and keeps outputs modular. This guide explains patterns, trade-offs, and tests for chains.

Patterns

• Extract-then-generate: First call extracts structured fields (entities, dates, classification). The second call generates human-facing text from the structured output. Advantage: clear boundary for testing and easier to validate.
• Retrieve-then-summarize: Fetch relevant documents, pass them (or their condensed excerpts) to the model, and ask for a summary with citations. Advantage: reduces hallucination if retrieval is precise.
• Classifier gating: Use a lightweight classifier to decide which specialized generator to call (e.g., billing vs. technical support response flows).
• Tool orchestration: Models call external tools (calculators, search, databases) and then synthesize results. Keep tool outputs structured and limited to reduce accidental exposure.
• Human-in-loop checkpoint: For high-risk outputs, insert a review step where a human accepts, edits, or rejects a draft before finalization.

Operational safeguards

• Idempotency: Ensure repeated calls with the same input produce stable structured outputs or allow deterministic post-processing.
• Version and schema control: Tag structured outputs with schema version and require validation before downstream consumption.
• Latency and cost: Minimize expensive calls in hot paths; prefer single-step generation for low-risk outputs.
• Error handling: Define fallback behaviors: retry, degrade to a safe template, or escalate to a human reviewer.

Testing chained workflows

1. Unit-test each step with representative inputs (happy path, ambiguous, adversarial).
2. Assert schema conformance for intermediate structured outputs.
3. End-to-end test the final user-facing output for clarity, accuracy, and safety.
4. Monitor drift: sample and replay production inputs periodically to catch regressions.

Example: Triage pipeline

1) Extract: Parse incoming message into {issue_type, urgency, affected_system}. 2) Classify: Map issue_type to queue (billing, infra, product). 3) Generate: Produce a reply template customized by queue, with next steps. 4) Human checkpoint for high-urgency or high-impact cases.

Chaining makes complex tasks tractable, but it increases maintenance points. Favor simple chains with clear interfaces and build tests for each interface.