MCP Python SDK v2 Stable Release
This is v2.0.0, the stable v2 release of the MCP Python SDK. It supports the 2026-07-28 revision of the Model Context Protocol and serves every earlier revision from the same server. pip install mcp now installs 2.x.
pip install "mcp[cli]"
# or
uv add "mcp[cli]"Documentation Rewrite
The documentation has the full tutorial and API reference. Coming from v1? What's new in v2 is the tour of what changed and why, and the migration guide lists every breaking change with before-and-after code.
V1 Maintenance mode
v1.x is in maintenance mode and will only receive security fixes from now on The 1.x line lives on the v1.x branch, continues to receive critical bug fixes and security patches, and is documented at https://py.sdk.modelcontextprotocol.io/v1/. If your project is not ready to migrate, keep a <2 upper bound on your requirement (for example mcp>=1.28,<2).
Highlights
One SDK, both protocol eras
v2 speaks the 2026-07-28 revision (stateless requests with no handshake, server/discover, subscriptions/listen, multi-round-trip requests) and still serves every 2025-era client from the same MCPServer, over Streamable HTTP and stdio, with nothing to configure. Client(target) negotiates the version automatically.
FastMCP is now MCPServer, and there is a first-class Client
The decorator API is unchanged; the low-level Server is rebuilt around a shared dispatcher engine, and one Client object replaces v1's transport-plus-ClientSession-plus-initialize() layering. It connects to a URL, a stdio subprocess, a custom transport, or straight to a server object in memory for tests.
Multi-round-trip requests and resolver dependency injection
At 2026-07-28 the server can no longer call the client, so tools return the question instead. A Resolve(fn) parameter is filled by your function invisibly to the model and can put a question to the user; one tool body serves both eras.
Extension APIs, OpenTelemetry, and a standalone types package
Servers and clients compose protocol extensions through pluggable extension APIs (MCP Apps built in); OpenTelemetry tracing ships on by default; every protocol type is its own package, mcp-types (imported as mcp_types), published in lock-step with mcp.
Hardened stdio and auth
stdio servers keep handler subprocesses and stray prints off the wire, and stdout is diverted to stderr while serving. OAuth adds RFC 9207 issuer validation, the SEP-990 identity-assertion flow, and the client-credentials extension.
Coming from a v2 pre-release
Since the last release candidate: the per-version wire packages are private (mcp_types._v*), mcp.types is a permanent alias for mcp_types, the auth registration request model is split from the registered-client record, cancelled requests are no longer answered, and log notifications are gated on the per-request log-level opt-in at 2026-07-28. Since the betas: Client(cache=False) is now cache=None with CacheConfig() the default; Context.client_id, RFC7523OAuthClientProvider, and OAuthClientProvider(timeout=) are removed; the client-credentials providers take scope=; message_handler receives notifications and exceptions only; FileResource(is_binary=) becomes encoding; MCP_* env vars are gone with pydantic-settings; Streamable HTTP servers reject bodies over 4 MiB with HTTP 413. The migration guide covers all of it.
Known gaps
The tasks extension (SEP-2663) is not part of this release. On the client, the DPoP proof binding (SEP-1932) and the workload-identity jwt-bearer grant are not implemented; both are additive and can land in 2.x.
Feedback
Something rough, confusing, or broken? Open an issue or find us in #python-sdk-dev on the MCP Contributors Discord.
Full Changelog: v2.0.0rc1...v2.0.0