v1.28.0

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