Mirror mcp_types.methods and .jsonrpc under mcp.types too

Main now declares the supported mcp_types import surface as the package
plus its jsonrpc, methods, and version submodules, and the "import
through the package you depend on" rule only holds if every one of
those has an mcp.types spelling. Otherwise an SDK user who needs
CACHEABLE_METHODS is straight back to a transitive import.

Add mcp.types.jsonrpc and mcp.types.methods mirrors alongside
.version, give mcp_types.jsonrpc an explicit __all__ so the mirror is
precise, and bind all three submodules on the mcp.types package so
`mcp.types.version.X` is attribute-reachable exactly like
`mcp_types.version.X` (previously only the from-import form worked).
Pin the whole mirror set with one parametrized parity test, and drop
the tautological __all__ equality (the mirror shares the source list
object by construction) plus a sed artifact in the migration guide.

Author: maxisbey

docs/migration.md

@@ -1730,7 +1730,7 @@ except MCPError as e:
         raise
 ```
 
-`e.error.code` also still works; `e.code` is the v2 convenience property. The constant is importable from `mcp.types` or, equivalently, `mcp.types`. The example uses the high-level `Client`; `ClientSession.call_tool()` raises the same `MCPError`.
+`e.error.code` also still works; `e.code` is the v2 convenience property. The constant is importable from `mcp.types` (or from `mcp_types` in a project that uses that package without the SDK). The example uses the high-level `Client`; `ClientSession.call_tool()` raises the same `MCPError`.
 
 ### `ClientSession` now runs on `JSONRPCDispatcher`; `BaseSession` removed
 

src/mcp-types/mcp_types/jsonrpc.py

@@ -6,6 +6,29 @@
 
 from pydantic import BaseModel, Field, TypeAdapter
 
+__all__ = [
+    "CONNECTION_CLOSED",
+    "HEADER_MISMATCH",
+    "INTERNAL_ERROR",
+    "INVALID_PARAMS",
+    "INVALID_REQUEST",
+    "JSONRPC_VERSION",
+    "METHOD_NOT_FOUND",
+    "MISSING_REQUIRED_CLIENT_CAPABILITY",
+    "PARSE_ERROR",
+    "REQUEST_TIMEOUT",
+    "UNSUPPORTED_PROTOCOL_VERSION",
+    "URL_ELICITATION_REQUIRED",
+    "ErrorData",
+    "JSONRPCError",
+    "JSONRPCMessage",
+    "JSONRPCNotification",
+    "JSONRPCRequest",
+    "JSONRPCResponse",
+    "RequestId",
+    "jsonrpc_message_adapter",
+]
+
 RequestId = Annotated[int, Field(strict=True)] | str
 """The ID of a JSON-RPC request."""
 

src/mcp/types/__init__.py

@@ -7,8 +7,10 @@
 
     types.TextContent(type="text", text="hi")
 
-The protocol-version registry lives in the `mcp.types.version` submodule,
-mirroring `mcp_types.version` the same way.
+The `mcp.types.jsonrpc`, `mcp.types.methods`, and `mcp.types.version`
+submodules mirror `mcp_types.jsonrpc`, `mcp_types.methods`, and
+`mcp_types.version` the same way, so every supported `mcp_types` import has
+an `mcp.types` spelling.
 
 Depend on and import `mcp_types` directly instead when you only need to
 (de)serialize MCP traffic and don't want the SDK's transport stack: its only
@@ -21,6 +23,13 @@
 from mcp_types import *
 from mcp_types import __all__ as __all__
 
+# Bind the mirror submodules on the package, so `mcp.types.version.X` is as
+# reachable by attribute access as `mcp_types.version.X` (whose `__init__`
+# binds `.version` by importing from it), not only via `from ... import`.
+from . import jsonrpc as jsonrpc
+from . import methods as methods
+from . import version as version
+
 # Names v1's mcp.types exposed that no longer exist. A bare "cannot import name"
 # leaves people grepping; naming the replacement finishes the migration step.
 _REMOVED = {

src/mcp/types/jsonrpc.py

@@ -0,0 +1,13 @@
+"""The JSON-RPC 2.0 message and error types, as the `mcp.types.jsonrpc` namespace.
+
+A mirror of `mcp_types.jsonrpc` (every name is the same object), so code that
+depends on `mcp` can import from `mcp.types.jsonrpc` without importing the
+`mcp_types` distribution directly. Depend on and import `mcp_types.jsonrpc`
+instead when you use `mcp-types` without the SDK.
+"""
+
+# A wildcard mirror of the mcp_types.jsonrpc namespace is the whole point of this module.
+# pyright: reportWildcardImportFromLibrary=false
+
+from mcp_types.jsonrpc import *
+from mcp_types.jsonrpc import __all__ as __all__

src/mcp/types/methods.py

@@ -0,0 +1,13 @@
+"""The MCP method registry, as the `mcp.types.methods` namespace.
+
+A mirror of `mcp_types.methods` (every name is the same object), so code that
+depends on `mcp` can import from `mcp.types.methods` without importing the
+`mcp_types` distribution directly. Depend on and import `mcp_types.methods`
+instead when you use `mcp-types` without the SDK.
+"""
+
+# A wildcard mirror of the mcp_types.methods namespace is the whole point of this module.
+# pyright: reportWildcardImportFromLibrary=false
+
+from mcp_types.methods import *
+from mcp_types.methods import __all__ as __all__

tests/test_types.py

@@ -1,8 +1,11 @@
 import subprocess
 import sys
+from types import ModuleType
 from typing import Any
 
 import mcp_types
+import mcp_types.jsonrpc
+import mcp_types.methods
 import mcp_types.version
 import pytest
 from inline_snapshot import snapshot
@@ -44,6 +47,8 @@
 
 import mcp
 import mcp.types
+import mcp.types.jsonrpc
+import mcp.types.methods
 import mcp.types.version
 
 
@@ -455,10 +460,29 @@ def test_input_required_result_requires_at_least_one_of_input_requests_or_reques
     assert InputRequiredResult(request_state="s").input_requests is None
 
 
+def _assert_mirrors(mirror: ModuleType, source: ModuleType) -> None:
+    # The mirror shares the source's `__all__` list object by construction (`from source import
+    # __all__`), so the meaningful proof is that every exported name is the identical object.
+    assert all(getattr(mirror, name) is getattr(source, name) for name in source.__all__)
+
+
 def test_mcp_types_namespace_mirrors_mcp_types_exactly():
     """SDK-defined: `mcp.types` is a permanent alias whose every name is the `mcp_types` object."""
-    assert mcp.types.__all__ == mcp_types.__all__
-    assert all(getattr(mcp.types, name) is getattr(mcp_types, name) for name in mcp_types.__all__)
+    _assert_mirrors(mcp.types, mcp_types)
+
+
+@pytest.mark.parametrize(
+    ("mirror", "source"),
+    [
+        (mcp.types.jsonrpc, mcp_types.jsonrpc),
+        (mcp.types.methods, mcp_types.methods),
+        (mcp.types.version, mcp_types.version),
+    ],
+    ids=["jsonrpc", "methods", "version"],
+)
+def test_mcp_types_submodules_mirror_mcp_types_submodules_exactly(mirror: ModuleType, source: ModuleType):
+    """SDK-defined: every supported `mcp_types` submodule has an `mcp.types` mirror, name for name."""
+    _assert_mirrors(mirror, source)
 
 
 def test_mcp_types_attribute_access_names_the_replacement_for_a_removed_name():
@@ -505,11 +529,3 @@ def test_bare_import_mcp_binds_the_types_submodule():
     )
     assert result.returncode == 0, result.stderr
     assert result.stdout == snapshot("Tool\n")
-
-
-def test_mcp_types_version_mirrors_mcp_types_version_exactly():
-    """SDK-defined: `mcp.types.version` is a permanent alias whose every name is the `mcp_types.version` object."""
-    assert mcp.types.version.__all__ == mcp_types.version.__all__
-    assert all(
-        getattr(mcp.types.version, name) is getattr(mcp_types.version, name) for name in mcp_types.version.__all__
-    )