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

Summary

agent-framework currently caps the MCP Python SDK below 2.0 (mcp>=1.24.0,<2), so it cannot be installed alongside mcp 2.0.0 (released 2026-07-28). The pin is load-bearing and correct today, but lifting it to support 2.x requires the code changes below.

Current constraint

mcp>=1.24.0,<2 — python/packages/core/pyproject.toml:35.

Breaking changes in mcp 2.0 that affect agent-framework

All client-side, in python/packages/core/agent_framework/_mcp.py, verified against the installed mcp==2.0.0 SDK:

1. McpError renamed → MCPError. Imported from mcp.shared.exceptions and used in many handlers: _mcp.py:1980, 2088, 2107, 2109, 2113, 2210, 2226, 2228, 2300, 2327, 2366, 2378, 2458, 2470, 2500, 2505, 2593, 2597, 2618, 2654. In 2.0 the name is MCPError (constructor MCPError(code, message, data=None)).

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

   • _mcp.py:1339-1341 — pass a float of seconds instead of timedelta.

3. camelCase attribute reads on mcp.types → snake_case (extensive):

   • .mimeType → mime_type: _mcp.py:588, 603, 660, 668, 678, 733, 741, 781
   • .structuredContent → structured_content: _mcp.py:691, 692, 760
   • .isError → is_error: _mcp.py:761, 2093, 2241, 2436
   • .inputSchema → input_schema: _mcp.py:1534, 1861

Notes

• The streamable-HTTP transport layer is already 2.0-ready: _mcp.py:361-374 uses the new streamable_http_client name with the http_client= kwarg and a 2-tuple-compatible result, so that part needs no change.
• 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.