modelcontextprotocol/python-sdk v2.0.0b1
Pre-releases are opt-in only; pip install mcp still resolves to the stable 1.x line.
Key points
- Beta means the architecture is settled and changes from here should be much smaller than between alphas, but the API can still shift before stable v2, targeted for 2026-07-28 alongside the spec release - keep pinning an exact version.
- A new core. The session-centric v1 internals are replaced by a dispatcher/runner pipeline built for the stateless 2026 protocol: ServerRunner is a pure handler kernel, transports are thin drivers over it, and one endpoint serves both protocol eras side by side.
- FastMCP is now MCPServer. The decorator API stays; the low-level Server takes handlers as constructor parameters, fields are snakecase, and traffic is validated against the negotiated spec version on the wire.
- Protocol types are a standalone package. mcp-types (imported as mcptypes) depends only on pydantic and typing-extensions, so tooling can speak MCP without the transport stack.
Sources (1)
- [1]modelcontextprotocol/python-sdk v2.0.0b1GitHub: modelcontextprotocol/python-sdk · Jun 30, 11:18 PM
Pre-releases are opt-in only; `pip install mcp` still resolves to the stable 1.x line.
Beta means the architecture is settled and changes from here should be much smaller than between alphas, but the API can still shift before stable v2, targeted for 2026-07-28 alongside the spec release - keep pinning an exact version.
Extractive summary: sentences quoted from the sources.