Python: support mcp 2.x (Python SDK): pin blocks mcp 2.0.0

Summary

semantic-kernel currently pins the MCP Python SDK to the 1.x line and cannot be installed alongside mcp 2.0.0 (released 2026-07-28). This issue tracks the breaking changes in mcp 2.0 that affect the Python MCP connector.

Current pins

• mcp>=1.26.0,<2.0 — python/pyproject.toml:59
• mcp>=1.8,<2.0 — python/pyproject.toml:99 (the mcp extra)

Breaking changes in mcp 2.0 that affect semantic-kernel

All in python/semantic_kernel/connectors/mcp.py, verified against the installed mcp==2.0.0 SDK:

1. streamablehttp_client renamed → streamable_http_client, and dropped kwargs.

   • mcp.py:20 — from mcp.client.streamable_http import streamablehttp_client
   • mcp.py:897 — return streamablehttp_client(**args) where args includes headers, timeout, sse_read_timeout (mcp.py:887-895). In 2.0 these kwargs are removed; headers/timeouts must move onto an httpx2.AsyncClient passed as http_client=.

2. ClientSession(read_timeout_seconds=timedelta(...)) now takes a float.

   • mcp.py:337 — read_timeout_seconds=timedelta(seconds=self.request_timeout) → pass a float of seconds.

3. McpError renamed → MCPError.

   • mcp.py:24 — from mcp.shared.exceptions import McpError; used at mcp.py:619, 637, 1125, 1158. In 2.0 the name is MCPError (constructor MCPError(code, message, data=None)).

4. camelCase attribute reads on mcp.types → snake_case.

   • mcp.py:113, 115, 120 — mcp_type.mimeType → mime_type
   • mcp.py:133 — mcp_type.toolUseId → tool_use_id
   • mcp.py:207, 208 — tool.inputSchema.get(...) → input_schema

5. Lowlevel @server.list_tools() / @server.call_tool() decorators removed.

   • mcp.py:1091 — @server.list_tools(); mcp.py:1118 — @server.call_tool() (in the MCPServer class, from mcp.server.lowlevel import Server at mcp.py:22). In 2.0 handlers are registered via the Server(...) constructor (on_list_tools= / on_call_tool=).

Notes

• Dependency-floor updates. mcp 2.0 requires pydantic>=2.12, anyio>=4.9, typing-extensions>=4.13, and adds required deps opentelemetry-api and mcp-types (exact-pinned to the SDK version); the SDK's HTTP layer moved from httpx/httpx-sse to httpx2>=2.5.0.

Happy to help with a PR if the maintainers are open to it.

Start with the dependency pins at python/pyproject.toml:59 and :99, then inspect the affected imports, attribute reads, client setup, and server handlers in python/semantic_kernel/connectors/mcp.py. Check the mcp 2.0 SDK interfaces described in the issue and verify that installation and the Python MCP connector work with mcp==2.0.0 and its required dependency floors.