modelcontextprotocol/python-sdk v1.28.0

on GitHub

Deprecations

Two API surfaces now emit DeprecationWarning ahead of their removal in v2. Nothing is removed in 1.x, and the warnings fire only when the deprecated API is called - importing the modules stays silent.

• WebSocket transport - mcp.client.websocket.websocket_client and mcp.server.websocket.websocket_server. WebSocket was never part of the MCP specification; use the streamable HTTP transport instead. The TypeScript SDK has likewise removed its WebSocket client for v2 (modelcontextprotocol/typescript-sdk#1783).
• Experimental tasks API - ClientSession.experimental, Server.experimental, ServerSession.experimental, and the experimental_task_handlers= kwarg on ClientSession. Tasks (SEP-1686) were removed from the MCP specification and are expected to return as a separate MCP extension.

If your test suite runs with filterwarnings = ["error"] and exercises these paths, add a scoped ignore such as ignore:The experimental tasks API is deprecated:DeprecationWarning or ignore:The WebSocket .* transport is deprecated:DeprecationWarning.

See #2828 for full details.

What's Changed

• [v1.x] Support Python 3.14 by @maxisbey in #2769
• fix: omit null optional fields from task result payloads by @liuzemei in #2809
• [v1.x] Deprecate the WebSocket transport and the experimental tasks entry points by @maxisbey in #2828
• [v1.x] Add a v2 status banner to the README by @maxisbey in #2835
• [v1.x] Deflake the child process cleanup tests by @maxisbey in #2839

New Contributors

• @liuzemei made their first contribution in #2809

Full Changelog: v1.27.2...v1.28.0