Remove helper types

The helper types in mcp.server.types got really confusioning during
implementation as they overlapped with mcp.types. I now believe it
is better if we stay more low level to the spec types.

To do this, we now only use mcp.types everywhere. We renamed mcp.server.types
to mcp.server.models and removed it to the absolute minimum.

src/mcp/server/__init__.py

@@ -7,7 +7,7 @@ from typing import Any, Sequence
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
 from pydantic import AnyUrl
 
-from mcp.server import types
+from mcp.server.models import InitializationOptions
 from mcp.server.session import ServerSession
 from mcp.server.stdio import stdio_server as stdio_server
 from mcp.shared.context import RequestContext
@@ -15,6 +15,10 @@ from mcp.shared.session import RequestResponder
 from mcp.types import (
     METHOD_NOT_FOUND,
     CallToolRequest,
+    GetPromptResult,
+    GetPromptRequest,
+    GetPromptResult,
+    ImageContent,
     ClientNotification,
     ClientRequest,
     CompleteRequest,
@@ -84,7 +88,7 @@ class Server:
         self,
         notification_options: NotificationOptions | None = None,
         experimental_capabilities: dict[str, dict[str, Any]] | None = None,
-    ) -> types.InitializationOptions:
+    ) -> InitializationOptions:
         """Create initialization options from this server instance."""
 
         def pkg_version(package: str) -> str:
@@ -99,7 +103,7 @@ class Server:
 
             return "unknown"
 
-        return types.InitializationOptions(
+        return InitializationOptions(
             server_name=self.name,
             server_version=pkg_version("mcp"),
             capabilities=self.get_capabilities(
@@ -168,50 +172,16 @@ class Server:
         return decorator
 
     def get_prompt(self):
-        from mcp.types import (
-            GetPromptRequest,
-            GetPromptResult,
-            ImageContent,
-        )
-        from mcp.types import (
-            Role as Role,
-        )
-
         def decorator(
             func: Callable[
-                [str, dict[str, str] | None], Awaitable[types.PromptResponse]
+                [str, dict[str, str] | None], Awaitable[GetPromptResult]
             ],
         ):
             logger.debug("Registering handler for GetPromptRequest")
 
             async def handler(req: GetPromptRequest):
                 prompt_get = await func(req.params.name, req.params.arguments)
-                messages: list[PromptMessage] = []
+                return ServerResult(prompt_get)
-                for message in prompt_get.messages:
-                    match message.content:
-                        case str() as text_content:
-                            content = TextContent(type="text", text=text_content)
-                        case types.ImageContent() as img_content:
-                            content = ImageContent(
-                                type="image",
-                                data=img_content.data,
-                                mimeType=img_content.mime_type,
-                            )
-                        case types.EmbeddedResource() as resource:
-                            content = EmbeddedResource(
-                                type="resource", resource=resource.resource
-                            )
-                        case _:
-                            raise ValueError(
-                                f"Unexpected content type: {type(message.content)}"
-                            )
-
-                    prompt_message = PromptMessage(role=message.role, content=content)
-                    messages.append(prompt_message)
-
-                return ServerResult(
-                    GetPromptResult(description=prompt_get.desc, messages=messages)
-                )
 
             self.request_handlers[GetPromptRequest] = handler
             return func
@@ -338,7 +308,7 @@ class Server:
         def decorator(
             func: Callable[
                 ...,
-                Awaitable[Sequence[str | types.ImageContent | types.EmbeddedResource]],
+                Awaitable[Sequence[TextContent | ImageContent | EmbeddedResource]],
             ],
         ):
             logger.debug("Registering handler for CallToolRequest")
@@ -351,15 +321,15 @@ class Server:
                         match result:
                             case str() as text:
                                 content.append(TextContent(type="text", text=text))
-                            case types.ImageContent() as img:
+                            case ImageContent() as img:
                                 content.append(
                                     ImageContent(
                                         type="image",
                                         data=img.data,
-                                        mimeType=img.mime_type,
+                                        mimeType=img.mimeType,
                                     )
                                 )
-                            case types.EmbeddedResource() as resource:
+                            case EmbeddedResource() as resource:
                                 content.append(
                                     EmbeddedResource(
                                         type="resource", resource=resource.resource
@@ -427,7 +397,7 @@ class Server:
         self,
         read_stream: MemoryObjectReceiveStream[JSONRPCMessage | Exception],
         write_stream: MemoryObjectSendStream[JSONRPCMessage],
-        initialization_options: types.InitializationOptions,
+        initialization_options: InitializationOptions,
         # When True, exceptions are returned as messages to the client.
         # When False, exceptions are raised, which will cause the server to shut down
         # but also make tracing exceptions much easier during testing and when using

src/mcp/server/__main__.py

@@ -6,7 +6,7 @@ import anyio
 
 from mcp.server.session import ServerSession
 from mcp.server.stdio import stdio_server
-from mcp.server.types import InitializationOptions
+from mcp.server.models import InitializationOptions
 from mcp.types import ServerCapabilities
 
 if not sys.warnoptions:

src/mcp/server/models.py

@@ -0,0 +1,19 @@
+"""
+This module provides simpler types to use with the server for managing prompts
+and tools.
+"""
+
+from dataclasses import dataclass
+from typing import Literal
+
+from pydantic import BaseModel
+
+from mcp.types import (
+    ServerCapabilities,
+)
+
+
+class InitializationOptions(BaseModel):
+    server_name: str
+    server_version: str
+    capabilities: ServerCapabilities

src/mcp/server/session.py

@@ -6,7 +6,7 @@ import anyio.lowlevel
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
 from pydantic import AnyUrl
 
-from mcp.server.types import InitializationOptions
+from mcp.server.models import InitializationOptions
 from mcp.shared.session import (
     BaseSession,
     RequestResponder,

src/mcp/server/types.py

@@ -1,46 +0,0 @@
-"""
-This module provides simpler types to use with the server for managing prompts
-and tools.
-"""
-
-from dataclasses import dataclass
-from typing import Literal
-
-from pydantic import BaseModel
-
-from mcp.types import (
-    BlobResourceContents,
-    Role,
-    ServerCapabilities,
-    TextResourceContents,
-)
-
-
-@dataclass
-class ImageContent:
-    type: Literal["image"]
-    data: str
-    mime_type: str
-
-
-@dataclass
-class EmbeddedResource:
-    resource: TextResourceContents | BlobResourceContents
-
-
-@dataclass
-class Message:
-    role: Role
-    content: str | ImageContent | EmbeddedResource
-
-
-@dataclass
-class PromptResponse:
-    messages: list[Message]
-    desc: str | None = None
-
-
-class InitializationOptions(BaseModel):
-    server_name: str
-    server_version: str
-    capabilities: ServerCapabilities

tests/conftest.py

@@ -2,7 +2,7 @@ import pytest
 from pydantic import AnyUrl
 
 from mcp.server import Server
-from mcp.server.types import InitializationOptions
+from mcp.server.models import InitializationOptions
 from mcp.types import Resource, ServerCapabilities
 
 TEST_INITIALIZATION_OPTIONS = InitializationOptions(

tests/server/test_session.py

@@ -4,7 +4,7 @@ import pytest
 from mcp.client.session import ClientSession
 from mcp.server import NotificationOptions, Server
 from mcp.server.session import ServerSession
-from mcp.server.types import InitializationOptions
+from mcp.server.models import InitializationOptions
 from mcp.types import (
     ClientNotification,
     InitializedNotification,

uv.lock

@@ -331,15 +331,14 @@ wheels = [
 
 [[package]]
 name = "pyright"
-version = "1.1.388"
+version = "1.1.378"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "nodeenv" },
-    { name = "typing-extensions" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/9c/83/e9867538a794638d2d20ac3ab3106a31aca1d9cfea530c9b2921809dae03/pyright-1.1.388.tar.gz", hash = "sha256:0166d19b716b77fd2d9055de29f71d844874dbc6b9d3472ccd22df91db3dfa34", size = 21939 }
+sdist = { url = "https://files.pythonhosted.org/packages/3d/f0/e8aa5555410d88f898bef04da2102b0a9bf144658c98d34872e91621ced2/pyright-1.1.378.tar.gz", hash = "sha256:78a043be2876d12d0af101d667e92c7734f3ebb9db71dccc2c220e7e7eb89ca2", size = 17486 }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/03/57/7fb00363b7f267a398c5bdf4f55f3e64f7c2076b2e7d2901b3373d52b6ff/pyright-1.1.388-py3-none-any.whl", hash = "sha256:c7068e9f2c23539c6ac35fc9efac6c6c1b9aa5a0ce97a9a8a6cf0090d7cbf84c", size = 18579 },
+    { url = "https://files.pythonhosted.org/packages/38/c6/f0d4bc20c13b20cecfbf13c699477c825e45767f1dc5068137323f86e495/pyright-1.1.378-py3-none-any.whl", hash = "sha256:8853776138b01bc284da07ac481235be7cc89d3176b073d2dba73636cb95be79", size = 18222 },
 ]
 
 [[package]]