Meta found that a single AI agent loaded with all the domain knowledge hallucinated in production, so they split the system into a deliberately dumb router that only sequences work and runs reliability checks, plus 14 specialist agents that each handle one domain. The result cut column configuration prep from about a day to under an hour, with roughly two-thirds of changes landing without significant human edits.

• A single "know everything" agent degraded past a certain context size, cross-contaminating naming conventions and code patterns across data sources; the fix was giving the central agent less to do, not better prompts or a bigger context window.
• The orchestrator is 1,300 lines and does no domain work: it follows a fixed seven-step protocol where only one step involves LLM reasoning, and that step runs inside an isolated subagent.
• New use cases are added by writing new workflow templates that sequence the existing 14 subagents differently, so pipeline migration needed zero new agent code.