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99* `POST /v1/messages` with [streaming](https://docs.claude.com/en/api/streaming) and [tool use](https://docs.claude.com/en/docs/tool-use) is required.
1010* `GET /v1/models` is optional. If the gateway implements it, Claude Desktop on 3P auto-discovers available models; if not, set `inferenceModels` explicitly.
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12The gateway should also preserve [prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching). Cowork and Code sessions send `cache_control` breakpoints with each turn so that the provider can reuse the tool definitions, system prompt, and earlier turns of the conversation instead of reprocessing them. A gateway that forwards these fields, or translates them for its upstream provider, keeps that behavior. A gateway that strips `cache_control`, or that changes the system prompt or tool list from one request to the next, makes the provider reprocess the whole conversation on every turn at full input-token cost and higher latency. To verify, check the [usage fields](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#tracking-cache-performance) your gateway returns or logs for Claude Desktop traffic: after the first request of a session, `cache_read_input_tokens` should be well above zero on most requests. If it is zero on every request, review the gateway's request transformation and caching settings for the route that serves Claude models.
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1214## Choose an authentication approach
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1416| Scenario | Use | Notes |