René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"401 in Streamable HTTP should be handled gracefully","articleBody":"### Initial Checks\n\n- [x] I confirm that I'm using the latest version of MCP Python SDK\n- [x] I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue\n\n### Description\n\nCurrently, `streamable_http` will call `response.raise_for_status()` when handling POST requests. [(ref)](https://github.com/modelcontextprotocol/python-sdk/blob/9a8592e7d4d69b785df8b5d9d7b694cb6cbb149f/src/mcp/client/streamable_http.py#L278).\n\nThis means that a 401 will bubble up and cause the entire program to crash. \n\nWhile a 401 on server initialize could warrant an exception, we have a use case where a MCP server will return 401 for specific unauthorized operations, and allow others.\n\nThis should be handled gracefully, similar to how [`_handle_unexpected_content_type`](https://github.com/modelcontextprotocol/python-sdk/blob/9a8592e7d4d69b785df8b5d9d7b694cb6cbb149f/src/mcp/client/streamable_http.py#L340C15-L340C46) works, returning a JSONRPC message outlining an unauthorized exception was thrown.\n\nThis would let an agent or other client handle it instead of crashing the program.\n\n\n### Python \u0026 MCP Python SDK\n\n```Text\nPython 3.12 and MCP SDK v1.13.1\n```","author":{"url":"https://github.com/somaraani","@type":"Person","name":"somaraani"},"datePublished":"2025-08-22T21:31:45.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/1295/python-sdk/issues/1295"}