Split protocol types into a standalone mcp-types package (#2973)

tests/client/conftest.py

@@ -4,11 +4,11 @@ from typing import Any
 from unittest.mock import patch
 
 import pytest
+from mcp_types import JSONRPCNotification, JSONRPCRequest
 
 import mcp.shared.memory
 from mcp.client._transport import WriteStream
 from mcp.shared.message import SessionMessage
-from mcp.types import JSONRPCNotification, JSONRPCRequest
 
 
 class SpyMemoryObjectSendStream:

tests/client/test_client.py

@@ -8,20 +8,10 @@ from contextlib import asynccontextmanager, contextmanager
 from unittest.mock import patch
 
 import anyio
+import mcp_types as types
 import pytest
 from inline_snapshot import snapshot
-
-from mcp import MCPError, types
-from mcp.client._memory import InMemoryTransport
-from mcp.client._transport import TransportStreams
-from mcp.client.client import Client
-from mcp.client.streamable_http import streamable_http_client
-from mcp.server import Server, ServerRequestContext
-from mcp.server.mcpserver import MCPServer
-from mcp.shared.memory import MessageStream, create_client_server_memory_streams
-from mcp.shared.message import SessionMessage
-from mcp.shared.version import LATEST_HANDSHAKE_VERSION
-from mcp.types import (
+from mcp_types import (
     CallToolResult,
     EmptyResult,
     GetPromptResult,
@@ -42,6 +32,17 @@ from mcp.types import (
     Tool,
     ToolsCapability,
 )
+from mcp_types.version import LATEST_HANDSHAKE_VERSION
+
+from mcp import MCPError
+from mcp.client._memory import InMemoryTransport
+from mcp.client._transport import TransportStreams
+from mcp.client.client import Client
+from mcp.client.streamable_http import streamable_http_client
+from mcp.server import Server, ServerRequestContext
+from mcp.server.mcpserver import MCPServer
+from mcp.shared.memory import MessageStream, create_client_server_memory_streams
+from mcp.shared.message import SessionMessage
 from tests.interaction._connect import BASE_URL, mounted_app
 
 pytestmark = pytest.mark.anyio

tests/client/test_http_unicode.py

@@ -8,16 +8,16 @@ from collections.abc import AsyncIterator
 from contextlib import asynccontextmanager
 
 import httpx
+import mcp_types as types
 import pytest
+from mcp_types import TextContent, Tool
 from starlette.applications import Starlette
 from starlette.routing import Mount
 
-from mcp import types
 from mcp.client.session import ClientSession
 from mcp.client.streamable_http import streamable_http_client
 from mcp.server import Server, ServerRequestContext
 from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
-from mcp.types import TextContent, Tool
 from tests.interaction.transports import StreamingASGITransport
 
 # The in-process app is mounted at this origin purely so URLs are well-formed; nothing listens here.

tests/client/test_list_methods_cursor.py

@@ -1,11 +1,12 @@
 from collections.abc import Callable
 
+import mcp_types as types
 import pytest
+from mcp_types import ListToolsResult
 
-from mcp import Client, types
+from mcp import Client
 from mcp.server import Server, ServerRequestContext
 from mcp.server.mcpserver import MCPServer
-from mcp.types import ListToolsResult
 
 from .conftest import StreamSpyCollection
 

tests/client/test_list_roots_callback.py

@@ -1,11 +1,11 @@
 import pytest
+from mcp_types import INVALID_REQUEST, ListRootsResult, Root, TextContent
 from pydantic import FileUrl
 
 from mcp import Client
 from mcp.client import ClientRequestContext
 from mcp.server.mcpserver import Context, MCPServer
 from mcp.shared.exceptions import MCPError
-from mcp.types import INVALID_REQUEST, ListRootsResult, Root, TextContent
 
 
 @pytest.mark.anyio

tests/client/test_logging_callback.py

@@ -1,15 +1,16 @@
 from typing import Literal
 
+import mcp_types as types
 import pytest
-
-from mcp import Client, types
-from mcp.server.mcpserver import Context, MCPServer
-from mcp.shared.session import RequestResponder
-from mcp.types import (
+from mcp_types import (
     LoggingMessageNotificationParams,
     TextContent,
 )
 
+from mcp import Client
+from mcp.server.mcpserver import Context, MCPServer
+from mcp.shared.session import RequestResponder
+
 
 class LoggingCollector:
     def __init__(self):

tests/client/test_notification_response.py

@@ -7,16 +7,17 @@ that don't follow SDK conventions.
 import json
 
 import httpx
+import mcp_types as types
 import pytest
+from mcp_types import RootsListChangedNotification
 from starlette.applications import Starlette
 from starlette.requests import Request
 from starlette.responses import JSONResponse, Response
 from starlette.routing import Route
 
-from mcp import ClientSession, MCPError, types
+from mcp import ClientSession, MCPError
 from mcp.client.streamable_http import streamable_http_client
 from mcp.shared.session import RequestResponder
-from mcp.types import RootsListChangedNotification
 
 pytestmark = pytest.mark.anyio
 

tests/client/test_output_schema_validation.py

@@ -2,10 +2,7 @@ import logging
 from typing import Any
 
 import pytest
-
-from mcp import Client
-from mcp.server import Server, ServerRequestContext
-from mcp.types import (
+from mcp_types import (
     CallToolRequestParams,
     CallToolResult,
     ListToolsResult,
@@ -14,6 +11,9 @@ from mcp.types import (
     Tool,
 )
 
+from mcp import Client
+from mcp.server import Server, ServerRequestContext
+
 
 def _make_server(
     tools: list[Tool],

tests/client/test_probe.py

@@ -17,18 +17,9 @@ from typing import Any, cast
 
 import anyio
 import httpx
+import mcp_types as types
 import pytest
-
-from mcp import types
-from mcp.client._probe import _parse_supported, negotiate_auto
-from mcp.client.session import ClientSession
-from mcp.shared.exceptions import MCPError
-from mcp.shared.version import (
-    HANDSHAKE_PROTOCOL_VERSIONS,
-    LATEST_MODERN_VERSION,
-    MODERN_PROTOCOL_VERSIONS,
-)
-from mcp.types import (
+from mcp_types import (
     INTERNAL_ERROR,
     INVALID_REQUEST,
     METHOD_NOT_FOUND,
@@ -37,6 +28,15 @@ from mcp.types import (
     Implementation,
     ServerCapabilities,
 )
+from mcp_types.version import (
+    HANDSHAKE_PROTOCOL_VERSIONS,
+    LATEST_MODERN_VERSION,
+    MODERN_PROTOCOL_VERSIONS,
+)
+
+from mcp.client._probe import _parse_supported, negotiate_auto
+from mcp.client.session import ClientSession
+from mcp.shared.exceptions import MCPError
 
 pytestmark = pytest.mark.anyio
 

tests/client/test_sampling_callback.py

@@ -1,10 +1,5 @@
 import pytest
-
-from mcp import Client
-from mcp.client import ClientRequestContext
-from mcp.server.mcpserver import Context, MCPServer
-from mcp.shared.exceptions import MCPError
-from mcp.types import (
+from mcp_types import (
     INVALID_REQUEST,
     CreateMessageRequestParams,
     CreateMessageResult,
@@ -14,6 +9,11 @@ from mcp.types import (
     ToolUseContent,
 )
 
+from mcp import Client
+from mcp.client import ClientRequestContext
+from mcp.server.mcpserver import Context, MCPServer
+from mcp.shared.exceptions import MCPError
+
 
 @pytest.mark.anyio
 async def test_sampling_callback():

tests/client/test_session.py

@@ -7,21 +7,9 @@ from typing import Any, cast
 import anyio
 import anyio.abc
 import anyio.streams.memory
+import mcp_types as types
 import pytest
-from pydantic import FileUrl, ValidationError
-
-from mcp import MCPError, types
-from mcp.client import ClientRequestContext
-from mcp.client.client import Client
-from mcp.client.session import DEFAULT_CLIENT_INFO, ClientSession
-from mcp.server import Server, ServerRequestContext
-from mcp.shared.direct_dispatcher import create_direct_dispatcher_pair
-from mcp.shared.dispatcher import CallOptions, DispatchContext, OnNotify, OnRequest
-from mcp.shared.message import SessionMessage
-from mcp.shared.session import RequestResponder
-from mcp.shared.transport_context import TransportContext
-from mcp.shared.version import HANDSHAKE_PROTOCOL_VERSIONS, LATEST_HANDSHAKE_VERSION
-from mcp.types import (
+from mcp_types import (
     CONNECTION_CLOSED,
     INTERNAL_ERROR,
     INVALID_PARAMS,
@@ -44,6 +32,19 @@ from mcp.types import (
     client_notification_adapter,
     client_request_adapter,
 )
+from mcp_types.version import HANDSHAKE_PROTOCOL_VERSIONS, LATEST_HANDSHAKE_VERSION
+from pydantic import FileUrl, ValidationError
+
+from mcp import MCPError
+from mcp.client import ClientRequestContext
+from mcp.client.client import Client
+from mcp.client.session import DEFAULT_CLIENT_INFO, ClientSession
+from mcp.server import Server, ServerRequestContext
+from mcp.shared.direct_dispatcher import create_direct_dispatcher_pair
+from mcp.shared.dispatcher import CallOptions, DispatchContext, OnNotify, OnRequest
+from mcp.shared.message import SessionMessage
+from mcp.shared.session import RequestResponder
+from mcp.shared.transport_context import TransportContext
 
 _SendToClient = anyio.streams.memory.MemoryObjectSendStream[SessionMessage | Exception]
 _RecvFromClient = anyio.streams.memory.MemoryObjectReceiveStream[SessionMessage]

tests/client/test_session_concurrency.py

@@ -3,11 +3,7 @@
 import anyio
 import pytest
 from inline_snapshot import snapshot
-
-from mcp import Client
-from mcp.client import ClientRequestContext
-from mcp.server.mcpserver import Context, MCPServer
-from mcp.types import (
+from mcp_types import (
     CallToolResult,
     CreateMessageRequestParams,
     CreateMessageResult,
@@ -15,6 +11,10 @@ from mcp.types import (
     TextContent,
 )
 
+from mcp import Client
+from mcp.client import ClientRequestContext
+from mcp.server.mcpserver import Context, MCPServer
+
 pytestmark = pytest.mark.anyio
 
 

tests/client/test_session_group.py

@@ -2,10 +2,10 @@ import contextlib
 from unittest import mock
 
 import httpx
+import mcp_types as types
 import pytest
 
 import mcp
-from mcp import types
 from mcp.client.session_group import (
     ClientSessionGroup,
     ClientSessionParameters,

tests/client/test_stdio.py

@@ -26,6 +26,7 @@ import pytest
 import trio
 import trio.testing
 from anyio.streams.memory import MemoryObjectReceiveStream
+from mcp_types import CONNECTION_CLOSED, JSONRPCMessage, JSONRPCRequest, JSONRPCResponse
 
 from mcp.client import stdio
 from mcp.client._transport import ReadStream
@@ -42,7 +43,6 @@ from mcp.os.posix.utilities import terminate_posix_process_tree
 from mcp.os.win32.utilities import FallbackProcess
 from mcp.shared.exceptions import MCPError
 from mcp.shared.message import SessionMessage
-from mcp.types import CONNECTION_CLOSED, JSONRPCMessage, JSONRPCRequest, JSONRPCResponse
 
 # ---------------------------------------------------------------------------
 # In-process fake of the spawned server process

tests/client/test_streamable_http.py

@@ -13,11 +13,11 @@ import anyio
 import httpx
 import pytest
 from inline_snapshot import snapshot
+from mcp_types import METHOD_NOT_FOUND, JSONRPCError, JSONRPCNotification, JSONRPCRequest, JSONRPCResponse
 
 from mcp.client.streamable_http import streamable_http_client
 from mcp.shared.inbound import MCP_PROTOCOL_VERSION_HEADER, encode_header_value
 from mcp.shared.message import ClientMessageMetadata, SessionMessage
-from mcp.types import METHOD_NOT_FOUND, JSONRPCError, JSONRPCNotification, JSONRPCRequest, JSONRPCResponse
 
 
 @pytest.mark.parametrize(

tests/client/transports/test_memory.py

@@ -6,14 +6,15 @@ from typing import Any
 
 import anyio
 import anyio.lowlevel
+import mcp_types as types
 import pytest
+from mcp_types import ListResourcesResult, Resource
 
-from mcp import Client, types
+from mcp import Client
 from mcp.client import _memory
 from mcp.client._memory import InMemoryTransport
 from mcp.server import Server, ServerRequestContext
 from mcp.server.mcpserver import MCPServer
-from mcp.types import ListResourcesResult, Resource
 
 
 @pytest.fixture

tests/interaction/README.md

@@ -24,7 +24,7 @@ flows — with a single subprocess test for stdio.
   rewrite preserved behaviour; a passing test that pins the wrong output exactly does. Known
   divergences are recorded as data on the requirement (see below), not worked around in the test.
 - **Spec-mandated assertions, not implementation quirks.** Error *codes* are asserted against
-  the constants in `mcp.types`; error *message strings* are pinned only where they are the
+  the constants in `mcp_types`; error *message strings* are pinned only where they are the
   SDK's own deliberate output.
 - **No sleeps, no real I/O.** Concurrency is coordinated with `anyio.Event`; every wait that
   could hang is bounded by `anyio.fail_after(5)`. The HTTP and OAuth tests drive the Starlette
@@ -243,7 +243,7 @@ many requirements at once; if the assertions would be separate, write separate t
 |---|---|
 | the result of a transformation (arguments → output, exception → error result) | `result == snapshot(...)` of the full object, so any field the implementation adds or drops fails the test |
 | pass-through of an opaque value (`_meta`, cursors) | identity against the same variable that was sent — a snapshot of a pass-through value only matches the input because a human checked two literals correspond |
-| an error | `pytest.raises(MCPError)` and a snapshot of `exc.value.error` when the message is the SDK's own; a plain `==` on `.code` against the `mcp.types` constant when it is not |
+| an error | `pytest.raises(MCPError)` and a snapshot of `exc.value.error` when the message is the SDK's own; a plain `==` on `.code` against the `mcp_types` constant when it is not |
 | third-party output embedded in a result (validation messages) | the stable prefix only — never pin text that changes with a dependency upgrade |
 
 ### Notifications and concurrency

tests/interaction/_connect.py

@@ -14,6 +14,16 @@ from typing import Any, Protocol
 
 import httpx
 from httpx_sse import ServerSentEvent, aconnect_sse
+from mcp_types import (
+    ClientCapabilities,
+    Implementation,
+    InitializeRequestParams,
+    JSONRPCMessage,
+    JSONRPCRequest,
+    JSONRPCResponse,
+    jsonrpc_message_adapter,
+)
+from mcp_types.version import LATEST_HANDSHAKE_VERSION, MODERN_PROTOCOL_VERSIONS
 from starlette.applications import Starlette
 from starlette.requests import Request
 from starlette.responses import Response
@@ -31,16 +41,6 @@ from mcp.server.sse import SseServerTransport
 from mcp.server.streamable_http import EventStore
 from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
 from mcp.server.transport_security import TransportSecuritySettings
-from mcp.shared.version import LATEST_HANDSHAKE_VERSION, MODERN_PROTOCOL_VERSIONS
-from mcp.types import (
-    ClientCapabilities,
-    Implementation,
-    InitializeRequestParams,
-    JSONRPCMessage,
-    JSONRPCRequest,
-    JSONRPCResponse,
-    jsonrpc_message_adapter,
-)
 from tests.interaction.transports._bridge import StreamingASGITransport
 
 # The in-process app is mounted at this origin purely so URLs are well-formed; nothing listens here.

tests/interaction/_helpers.py

@@ -9,12 +9,12 @@ them.
 from types import TracebackType
 
 import anyio
+from mcp_types import ClientResult, ServerNotification, ServerRequest
 from typing_extensions import Self
 
 from mcp.client._transport import ReadStream, Transport, TransportStreams, WriteStream
 from mcp.shared.message import SessionMessage
 from mcp.shared.session import RequestResponder
-from mcp.types import ClientResult, ServerNotification, ServerRequest
 
 # TODO: this union is the parameter type of every client message handler (MessageHandlerFnT),
 # but the SDK does not export a name for it -- writing a correctly-typed handler requires

tests/interaction/_modern_vocab.py

@@ -18,8 +18,7 @@ assumptions about which side produced what.
 from dataclasses import dataclass
 
 import httpx
-
-from mcp.types import JSONRPCMessage, jsonrpc_message_adapter
+from mcp_types import JSONRPCMessage, jsonrpc_message_adapter
 
 #: Substrings that must not appear anywhere in a request body or JSON-RPC frame on a legacy
 #: exchange. Matching is by raw substring against the by-alias JSON serialisation, so a leaked