What the orchestrator does
An agentic workflow defines what should happen — research, verify, draft, QA. The orchestrator defines how it happens at runtime:
- Scheduling — which agent runs first, second, third
- Data routing — passing the output of one agent as input to the next
- Dependency resolution — ensuring prerequisites complete before dependent stages start
- Error handling — retrying failed stages, routing around errors, escalating when needed
- Resource management — managing API rate limits, model contexts, and concurrent executions
Without orchestration, an agentic workflow is just a list of tasks. With it, the list becomes an executable pipeline.
Sequential vs. parallel execution
The simplest orchestration pattern is sequential: stage A completes, its output feeds stage B, and so on. But real pipelines often benefit from parallelism.
Sequential: Research → Analyze → Draft → Verify → Output
Parallel: Research ──→ Analyze ──→ Draft ──→ Verify → Output
Research ──→ Fact-check ─────────↗
In the parallel case, research feeds both an analysis agent and a fact-checking agent simultaneously. Their outputs converge at the drafting stage. This reduces total pipeline time without sacrificing verification depth.
Key orchestration patterns
Fan-out / Fan-in
A single input is processed by multiple agents in parallel, and their outputs are merged:
- Fan-out: send the same source material to a research agent, a citation extractor, and a key-themes agent
- Fan-in: merge their outputs into a unified analysis that feeds the drafting stage
Conditional branching
The orchestrator routes execution based on intermediate results:
- If citation verification fails for more than 20% of sources → route back to the research agent for replacement sources
- If QA score is below threshold → re-run the drafting stage with stricter constraints
Retry with backoff
When an agent stage fails (API timeout, rate limit, malformed output), the orchestrator retries with exponential backoff before marking the stage as failed.
Why orchestration is infrastructure
Orchestration is not a feature — it's infrastructure. It sits below the application layer and handles concerns that individual agents shouldn't manage:
| Concern | Without Orchestration | With Orchestration |
|---|---|---|
| Execution order | Manual, fragile | Declarative, reliable |
| Error recovery | Entire pipeline fails | Graceful retry/reroute |
| Parallelism | Not possible | Automatic where defined |
| Observability | None | Full stage-by-stage logging |
| Reproducibility | Inconsistent | Same template → same pipeline |
Orchestration is what makes the difference between a demo and a production system. Demos can chain prompts manually. Production requires scheduling, error handling, and observability.
Observability
A well-orchestrated pipeline produces a complete execution trace:
- Stage timings — how long each agent took
- Input/output snapshots — what data entered and exited each stage
- Decision points — where conditional logic branched
- Error log — what failed, how many retries, whether recovery succeeded
- Final assembly — how the artifact was composed from stage outputs
This trace is what makes pipelines auditable — you can inspect exactly what happened, why, and where.