autogen-ext: mcp 2.0.0 breaks MCP tools (no upper bound, uses removed/renamed 1.x APIs)

Summary

The autogen-ext MCP integration does not cap the MCP Python SDK, so pip install autogen-ext[mcp] now resolves to mcp 2.0.0 (released 2026-07-28) — and the code breaks on it, because it uses several mcp 1.x APIs that were removed or renamed in 2.0. This is a live latent bug today, not just a future migration concern.

Current constraint

mcp = ["mcp>=1.11.0"] — python/packages/autogen-ext/pyproject.toml:153 (no upper bound).

Breaking changes in mcp 2.0 that affect autogen-ext

All client-side, in python/packages/autogen-ext/src/autogen_ext/tools/mcp/, verified against the installed mcp==2.0.0 SDK:

1. streamablehttp_client renamed → streamable_http_client, 3-tuple → 2-tuple, and dropped kwargs.

   • _session.py:9 — from mcp.client.streamable_http import streamablehttp_client; used at _session.py:50.
   • _session.py:50-54 — unpacks a 3-tuple as (read, write, session_id_callback); 2.0 returns only (read, write).
   • _session.py:47-48 — passes timeout= / sse_read_timeout= (as timedelta), both removed in 2.0; timeouts must move onto an httpx2.AsyncClient passed as http_client=.

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

   • _session.py:27, :38, :59 — pass a float of seconds instead of timedelta.

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

   • .inputSchema → input_schema: _base.py:50, _workbench.py:302-304
   • .isError → is_error: _base.py:122, _workbench.py:347

4. sse_client(**server_params.model_dump(...)) at _session.py:34 — passes the full params dict; if it includes kwargs removed in 2.0, this path also breaks and should be re-verified.

Notes

• Short term, capping mcp<2 would stop the breakage; the longer-term fix is the migration above.
• 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.