Unbounded mcp>=1.0.0 dependency resolves to MCP SDK 2.0, breaking the MCP server on import

[bgimbel]

Unbounded mcp>=1.0.0 dependency resolves to MCP SDK 2.0, which breaks the MCP server on import

Summary

pyproject.toml pins mcp>=1.0.0 with no upper bound. The MCP Python SDK has released 2.0.0, which removes/reorganizes the 1.x low-level Server decorator API that src/main.py uses. A fresh install today gets mcp 2.0.0 and the MCP server crashes on import, so every MCP host (Claude Code, etc.) shows the server as failed.

Environment

• open-brain installed via pipx install 'git+https://github.com/benclawbot/open-brain.git' (master as of 2026-07-31)
• Python 3.12; resolver selected mcp 2.0.0 + mcp_types 2.0.0

Reproduction

$ python -m src.main
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File ".../site-packages/src/main.py", line 53, in <module>
    @app.list_tools()
     ^^^^^^^^^^^^^^
AttributeError: 'Server' object has no attribute 'list_tools'

The process exits before the stdio handshake, so MCP clients report the server as failed with no useful diagnostics.

Root cause

dependencies = [
    "mcp>=1.0.0",
    ...
]

src/main.py uses the 1.x API (from mcp.server import Server, @app.list_tools() / @app.call_tool() decorators, mcp.server.stdio.stdio_server). In SDK 2.0 the low-level server surface changed (mcp.server now exports Server from lowlevel with a different interface, plus a new MCPServer), so the 1.x decorator calls fail at import time.

Suggested fix

Short term, cap the dependency:

"mcp>=1.0.0,<2",

Longer term, migrate src/main.py to the 2.x server API and bump the floor accordingly.

Workaround

$ pipx runpip openbrain install 'mcp>=1.0.0,<2'

(installs mcp 1.29.0; verified the server then completes the MCP initialize handshake and works from Claude Code.)