–Best-in-class function calling reliability — structured outputs via JSON mode rarely hallucinates field names
–Parallel tool calls in a single response reduces round-trips significantly
–Streaming is stable and well-documented; token-level streaming works reliably
–Assistants API thread management simplifies stateful multi-turn conversations
Cons
–Rate limits on Tier 1 accounts are aggressive — 10k RPM is hit fast in multi-agent fan-out
–Latency spikes during peak hours (8am–2pm US EST) — p99 can reach 8s on gpt-4o
–No native support for custom system-level memory injection without prompt engineering
–Batch API has 24h turnaround — not suitable for near-real-time pipelines
Use cases
–Structured data extraction
–Multi-step agentic workflows
–Code generation and review
–Embeddings for semantic search
Verdict
Best default choice for production agents requiring reliable structured output. Budget for Tier 2+ rate limits early. Use Batch API for cost savings on offline workloads.
