MCP Python SDK 发布: v2.0.0rc1

来源摘要

First v2 release candidate. Pre-releases are opt-in only; `pip install mcp` still resolves to the stable 1.x line. ```bash pip install mcp==2.0.0rc1 # or uv add "mcp==2.0.0rc1" ``` The [documentation](https://py.sdk.modelcontextprotocol.io/v2/) has the full tutorial and API reference, and the [migration guide](https://py.sdk.modelcontextprotocol.io/v2/migration/) covers coming from v1. Stable v2 is planned for 2026-07-28 alongside the spec release - keep pinning an exact version until then. ## Highlights ### API cleanup ahead of stable (breaking for beta users) The last pre-release pass over the public surface; every item has a migration guide entry. - `Client(cache=False)` is now `Client(cache=None)`: `CacheConfig()` is the default and `None` switches the response cache off (#3164). - `Context.client_id` is removed - read `_meta` via `ctx.request_context.meta`, or the authenticated client via `get_access_token().client_id` (#3167). - `RFC7523OAuthClientProvider` and `JWTParameters` are removed - use `ClientCredentialsOAuthProvider`, `PrivateKeyJWTOAuthProvider`, or `IdentityAssertionOAuthProvider` (#3169). - The client-credentials providers take `scope=`, not `scopes=` (#3166). - `OAuthClientProvider(timeout=...)` is removed; it never bounded anything (#3165). - `message_handler` receives `ServerNotification | Exception` only; the dead `RequestResponder` arm and the `mcp.shared.session` module are gone (#3168). - `FileResource(is_binary=...)` is replaced by `encoding: str | None` (#3171). - `MCP_*` environment variables never configured `MCPServer` and are no longer advertised; `pydantic-settings` is dropped from the runtime dependencies (#3170). - Streamable HTTP servers reject request bodies over 4 MiB with HTTP 413; raise `max_request_body_size` if you accept larger