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MCP Python SDK v2.0.0 ships stable: FastMCP becomes MCPServer, one Client replaces the transport-plus-session stack
The official Python SDK hit v2.0.0 on July 28 and `pip install mcp` now resolves to 2.x, with v1.x moved to security-fixes-only maintenance on a `v1.x` branch. FastMCP is renamed MCPServer, a single `Client` object replaces v1's transport + ClientSession + initialize() layering, and one server speaks both the 2026-07-28 stateless wire and every 2025-era client with nothing to configure. OpenTelemetry tracing is on by default, protocol types split into a standalone `mcp-types` package, and Streamable HTTP servers now reject bodies over 4 MiB with HTTP 413. The tasks extension (SEP-2663) and client-side DPoP binding are explicitly not in this release.
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