Maintenance: Bump mcp from 1.28.1 to 2.0.0 in /.engine

[dependabot]

Bumps mcp from 1.28.1 to 2.0.0.

Release notes

Sourced from mcp's releases.

v2.0.0

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

... (truncated)

Commits

• 6f69a37 Present v2 as the stable release across the README, docs, and policies (#3178)
• 78e6fbb Serve v2 docs at the site root, with permanent per-major paths (#3176)
• af06330 Remove unused StreamableHTTPTransport.get_session_id() (#3205)
• 68ca87e Document the two-line release process for stable v2 (#3179)
• c9c431b Expose the middleware chain on MCPServer and stop sending unrequested change ...
• 528e366 Fail fast on server-to-client requests in JSON-response mode instead of hangi...
• 27f5cc7 Remove unused mcpserver.exceptions.ValidationError (#3199)
• 89c5e70 Gate log notifications on the per-request log-level opt-in at 2026-07-28 (#3198)
• b61ce38 docs: fix off-by-one hl_lines in apps.md (#3196)
• b7c9a91 Add mcp.types as a permanent alias for mcp_types (#3190)
• Additional commits viewable in compare view

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[github-actions]

Heads-up: this pull request changes engine files the next engine update is set to overwrite.

The engine keeps its own machinery current by replacing these files wholesale when you update — so a change you make to them here won't survive the next update; it will quietly revert:

• .engine/pyproject.toml
• .engine/uv.lock

If that was a one-off, this is just so you know. If you want the change to last, the durable home for an edit to engine machinery is upstream in the engine project these files come from (StarshipSuperjam/engine-template) — a fix there travels to every update. And if what you actually want is to customize how the engine behaves, the settings that do survive an update are your tunable policy (via /engine-tune) and your operator notes — those are preserved; these files are not.

This is a heads-up only — it does not block your merge, and your merge is the decision.