Claude

We moved an LLM backend from Claude Sonnet 4.6 to Opus 4.8. The model is configurable through a single environment variable, so this should have been a one-line change. Instead, every call started returning HTTP 400. The error, once we read the full response body: anthropic.BadRequestError: Error code: 400 - {'type': 'error', 'error': {'type': 'invalid_request_error', 'message': '`temperature` is deprecated for this model.'}} Opus 4.8 no longer accepts the temperature parameter. Send it, even temperature=0.2, and the API rejects the whole request. Our code passed temperature on every call (a habit, for slightly more deterministic synthesis), so the model swap broke everything until we stopped sending it. ...

In a previous post we rebuilt our company knowledge base server from an MCP SSE endpoint to a plain FastAPI REST server because MCP client support was too fragmented to be reliable. The conclusion was: REST is the pragmatic choice, MCP can come back when the ecosystem matures. The ecosystem has matured faster than expected. We added MCP back on top of the FastAPI server and it now works across every client simultaneously: claude.ai, Claude Teams (company-wide), Claude desktop, ChatGPT, and OpenWebUI. This is what we learned in the process. ...