An LLM gateway can centralize provider credentials, model routing, quota enforcement, request validation, and telemetry. Token budgets include instructions, user input, retrieved context, tool output, and expected generation. A request that fits one model may exceed another model's context window.

Model routing can optimize cost, latency, capability, or availability, but fallback models may differ in quality and output format. Validate structured outputs and define timeouts, retries, and safe fallbacks. A provider may have completed a request even if the client lost the response, so repeated expensive calls need careful handling.

Apply per-tenant token and concurrency quotas. Track cost per successful task rather than only request count because prompt and output lengths vary substantially.