Add strict mode to pyright (#315)

* Add strict mode to pyright

* Apply UP rule

* fix readme

* More correct

* Leave wrong Context for now

* Add strict mode to pyright

* Apply UP rule

* fix readme

* fix

* ignore

Author: Kludex

Diff for: README.md

@@ -16,33 +16,36 @@
 <!-- omit in toc -->
 ## Table of Contents
 
-- [Overview](#overview)
-- [Installation](#installation)
-- [Quickstart](#quickstart)
-- [What is MCP?](#what-is-mcp)
-- [Core Concepts](#core-concepts)
-  - [Server](#server)
-  - [Resources](#resources)
-  - [Tools](#tools)
-  - [Prompts](#prompts)
-  - [Images](#images)
-  - [Context](#context)
-- [Running Your Server](#running-your-server)
-  - [Development Mode](#development-mode)
-  - [Claude Desktop Integration](#claude-desktop-integration)
-  - [Direct Execution](#direct-execution)
-  - [Mounting to an Existing ASGI Server](#mounting-to-an-existing-asgi-server)
-- [Examples](#examples)
-  - [Echo Server](#echo-server)
-  - [SQLite Explorer](#sqlite-explorer)
-- [Advanced Usage](#advanced-usage)
-  - [Low-Level Server](#low-level-server)
-  - [Writing MCP Clients](#writing-mcp-clients)
-  - [MCP Primitives](#mcp-primitives)
-  - [Server Capabilities](#server-capabilities)
-- [Documentation](#documentation)
-- [Contributing](#contributing)
-- [License](#license)
+- [MCP Python SDK](#mcp-python-sdk)
+  - [Overview](#overview)
+  - [Installation](#installation)
+    - [Adding MCP to your python project](#adding-mcp-to-your-python-project)
+    - [Running the standalone MCP development tools](#running-the-standalone-mcp-development-tools)
+  - [Quickstart](#quickstart)
+  - [What is MCP?](#what-is-mcp)
+  - [Core Concepts](#core-concepts)
+    - [Server](#server)
+    - [Resources](#resources)
+    - [Tools](#tools)
+    - [Prompts](#prompts)
+    - [Images](#images)
+    - [Context](#context)
+  - [Running Your Server](#running-your-server)
+    - [Development Mode](#development-mode)
+    - [Claude Desktop Integration](#claude-desktop-integration)
+    - [Direct Execution](#direct-execution)
+    - [Mounting to an Existing ASGI Server](#mounting-to-an-existing-asgi-server)
+  - [Examples](#examples)
+    - [Echo Server](#echo-server)
+    - [SQLite Explorer](#sqlite-explorer)
+  - [Advanced Usage](#advanced-usage)
+    - [Low-Level Server](#low-level-server)
+    - [Writing MCP Clients](#writing-mcp-clients)
+    - [MCP Primitives](#mcp-primitives)
+    - [Server Capabilities](#server-capabilities)
+  - [Documentation](#documentation)
+  - [Contributing](#contributing)
+  - [License](#license)
 
 [pypi-badge]: https://img.shields.io/pypi/v/mcp.svg
 [pypi-url]: https://pypi.org/project/mcp/
@@ -143,8 +146,8 @@ The FastMCP server is your core interface to the MCP protocol. It handles connec
 ```python
 # Add lifespan support for startup/shutdown with strong typing
 from contextlib import asynccontextmanager
+from collections.abc import AsyncIterator
 from dataclasses import dataclass
-from typing import AsyncIterator
 
 from fake_database import Database  # Replace with your actual DB type
 
@@ -442,7 +445,7 @@ For more control, you can use the low-level server implementation directly. This
 
 ```python
 from contextlib import asynccontextmanager
-from typing import AsyncIterator
+from collections.abc import AsyncIterator
 
 from fake_database import Database  # Replace with your actual DB type
 

Diff for: pyproject.toml

@@ -76,13 +76,11 @@ packages = ["src/mcp"]
 include = ["src/mcp", "tests"]
 venvPath = "."
 venv = ".venv"
-strict = [
-    "src/mcp/server/fastmcp/tools/base.py",
-    "src/mcp/client/*.py"
-]
+strict = ["src/mcp/**/*.py"]
+exclude = ["src/mcp/types.py"]
 
 [tool.ruff.lint]
-select = ["E", "F", "I"]
+select = ["E", "F", "I", "UP"]
 ignore = []
 
 [tool.ruff]

Diff for: src/mcp/cli/claude.py

@@ -4,6 +4,7 @@
 import os
 import sys
 from pathlib import Path
+from typing import Any
 
 from mcp.server.fastmcp.utilities.logging import get_logger
 
@@ -116,10 +117,7 @@ def update_claude_config(
         # Add fastmcp run command
         args.extend(["mcp", "run", file_spec])
 
-        server_config = {
-            "command": "uv",
-            "args": args,
-        }
+        server_config: dict[str, Any] = {"command": "uv", "args": args}
 
         # Add environment variables if specified
         if env_vars:

Diff for: src/mcp/client/websocket.py

@@ -1,7 +1,7 @@
 import json
 import logging
+from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
-from typing import AsyncGenerator
 
 import anyio
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream

Diff for: src/mcp/server/fastmcp/prompts/base.py

@@ -2,8 +2,8 @@
 
 import inspect
 import json
-from collections.abc import Callable
-from typing import Any, Awaitable, Literal, Sequence
+from collections.abc import Awaitable, Callable, Sequence
+from typing import Any, Literal
 
 import pydantic_core
 from pydantic import BaseModel, Field, TypeAdapter, validate_call
@@ -19,7 +19,7 @@ class Message(BaseModel):
     role: Literal["user", "assistant"]
     content: CONTENT_TYPES
 
-    def __init__(self, content: str | CONTENT_TYPES, **kwargs):
+    def __init__(self, content: str | CONTENT_TYPES, **kwargs: Any):
         if isinstance(content, str):
             content = TextContent(type="text", text=content)
         super().__init__(content=content, **kwargs)
@@ -30,7 +30,7 @@ class UserMessage(Message):
 
     role: Literal["user", "assistant"] = "user"
 
-    def __init__(self, content: str | CONTENT_TYPES, **kwargs):
+    def __init__(self, content: str | CONTENT_TYPES, **kwargs: Any):
         super().__init__(content=content, **kwargs)
 
 
@@ -39,11 +39,13 @@ class AssistantMessage(Message):
 
     role: Literal["user", "assistant"] = "assistant"
 
-    def __init__(self, content: str | CONTENT_TYPES, **kwargs):
+    def __init__(self, content: str | CONTENT_TYPES, **kwargs: Any):
         super().__init__(content=content, **kwargs)
 
 
-message_validator = TypeAdapter(UserMessage | AssistantMessage)
+message_validator = TypeAdapter[UserMessage | AssistantMessage](
+    UserMessage | AssistantMessage
+)
 
 SyncPromptResult = (
     str | Message | dict[str, Any] | Sequence[str | Message | dict[str, Any]]
@@ -73,12 +75,12 @@ class Prompt(BaseModel):
     arguments: list[PromptArgument] | None = Field(
         None, description="Arguments that can be passed to the prompt"
     )
-    fn: Callable = Field(exclude=True)
+    fn: Callable[..., PromptResult | Awaitable[PromptResult]] = Field(exclude=True)
 
     @classmethod
     def from_function(
         cls,
-        fn: Callable[..., PromptResult],
+        fn: Callable[..., PromptResult | Awaitable[PromptResult]],
         name: str | None = None,
         description: str | None = None,
     ) -> "Prompt":
@@ -99,7 +101,7 @@ def from_function(
         parameters = TypeAdapter(fn).json_schema()
 
         # Convert parameters to PromptArguments
-        arguments = []
+        arguments: list[PromptArgument] = []
         if "properties" in parameters:
             for param_name, param in parameters["properties"].items():
                 required = param_name in parameters.get("required", [])
@@ -138,25 +140,23 @@ async def render(self, arguments: dict[str, Any] | None = None) -> list[Message]
                 result = await result
 
             # Validate messages
-            if not isinstance(result, (list, tuple)):
+            if not isinstance(result, list | tuple):
                 result = [result]
 
             # Convert result to messages
-            messages = []
-            for msg in result:
+            messages: list[Message] = []
+            for msg in result:  # type: ignore[reportUnknownVariableType]
                 try:
                     if isinstance(msg, Message):
                         messages.append(msg)
                     elif isinstance(msg, dict):
-                        msg = message_validator.validate_python(msg)
-                        messages.append(msg)
+                        messages.append(message_validator.validate_python(msg))
                     elif isinstance(msg, str):
-                        messages.append(
-                            UserMessage(content=TextContent(type="text", text=msg))
-                        )
+                        content = TextContent(type="text", text=msg)
+                        messages.append(UserMessage(content=content))
                     else:
-                        msg = json.dumps(pydantic_core.to_jsonable_python(msg))
-                        messages.append(Message(role="user", content=msg))
+                        content = json.dumps(pydantic_core.to_jsonable_python(msg))
+                        messages.append(Message(role="user", content=content))
                 except Exception:
                     raise ValueError(
                         f"Could not convert prompt result to message: {msg}"

Diff for: src/mcp/server/fastmcp/resources/resource_manager.py

@@ -1,6 +1,7 @@
 """Resource manager functionality."""
 
-from typing import Callable
+from collections.abc import Callable
+from typing import Any
 
 from pydantic import AnyUrl
 
@@ -47,7 +48,7 @@ def add_resource(self, resource: Resource) -> Resource:
 
     def add_template(
         self,
-        fn: Callable,
+        fn: Callable[..., Any],
         uri_template: str,
         name: str | None = None,
         description: str | None = None,

Diff for: src/mcp/server/fastmcp/resources/templates.py

@@ -1,8 +1,11 @@
 """Resource template functionality."""
 
+from __future__ import annotations
+
 import inspect
 import re
-from typing import Any, Callable
+from collections.abc import Callable
+from typing import Any
 
 from pydantic import BaseModel, Field, TypeAdapter, validate_call
 
@@ -20,18 +23,20 @@ class ResourceTemplate(BaseModel):
     mime_type: str = Field(
         default="text/plain", description="MIME type of the resource content"
     )
-    fn: Callable = Field(exclude=True)
-    parameters: dict = Field(description="JSON schema for function parameters")
+    fn: Callable[..., Any] = Field(exclude=True)
+    parameters: dict[str, Any] = Field(
+        description="JSON schema for function parameters"
+    )
 
     @classmethod
     def from_function(
         cls,
-        fn: Callable,
+        fn: Callable[..., Any],
         uri_template: str,
         name: str | None = None,
         description: str | None = None,
         mime_type: str | None = None,
-    ) -> "ResourceTemplate":
+    ) -> ResourceTemplate:
         """Create a template from a function."""
         func_name = name or fn.__name__
         if func_name == "<lambda>":

Diff for: src/mcp/server/fastmcp/server.py

@@ -5,13 +5,13 @@
 import inspect
 import json
 import re
-from collections.abc import AsyncIterator, Iterable
+from collections.abc import AsyncIterator, Callable, Iterable, Sequence
 from contextlib import (
     AbstractAsyncContextManager,
     asynccontextmanager,
 )
 from itertools import chain
-from typing import Any, Callable, Generic, Literal, Sequence
+from typing import Any, Generic, Literal
 
 import anyio
 import pydantic_core
@@ -20,6 +20,7 @@
 from pydantic.networks import AnyUrl
 from pydantic_settings import BaseSettings, SettingsConfigDict
 from starlette.applications import Starlette
+from starlette.requests import Request
 from starlette.routing import Mount, Route
 
 from mcp.server.fastmcp.exceptions import ResourceError
@@ -88,13 +89,13 @@ class Settings(BaseSettings, Generic[LifespanResultT]):
     )
 
     lifespan: (
-        Callable[["FastMCP"], AbstractAsyncContextManager[LifespanResultT]] | None
+        Callable[[FastMCP], AbstractAsyncContextManager[LifespanResultT]] | None
     ) = Field(None, description="Lifespan context manager")
 
 
 def lifespan_wrapper(
     app: FastMCP,
-    lifespan: Callable[["FastMCP"], AbstractAsyncContextManager[LifespanResultT]],
+    lifespan: Callable[[FastMCP], AbstractAsyncContextManager[LifespanResultT]],
 ) -> Callable[[MCPServer[LifespanResultT]], AbstractAsyncContextManager[object]]:
     @asynccontextmanager
     async def wrap(s: MCPServer[LifespanResultT]) -> AsyncIterator[object]:
@@ -179,7 +180,7 @@ async def list_tools(self) -> list[MCPTool]:
             for info in tools
         ]
 
-    def get_context(self) -> "Context[ServerSession, object]":
+    def get_context(self) -> Context[ServerSession, object]:
         """
         Returns a Context object. Note that the context will only be valid
         during a request; outside a request, most methods will error.
@@ -478,9 +479,11 @@ def sse_app(self) -> Starlette:
         """Return an instance of the SSE server app."""
         sse = SseServerTransport("/messages/")
 
-        async def handle_sse(request):
+        async def handle_sse(request: Request) -> None:
             async with sse.connect_sse(
-                request.scope, request.receive, request._send
+                request.scope,
+                request.receive,
+                request._send,  # type: ignore[reportPrivateUsage]
             ) as streams:
                 await self._mcp_server.run(
                     streams[0],
@@ -535,14 +538,14 @@ def _convert_to_content(
     if result is None:
         return []
 
-    if isinstance(result, (TextContent, ImageContent, EmbeddedResource)):
+    if isinstance(result, TextContent | ImageContent | EmbeddedResource):
         return [result]
 
     if isinstance(result, Image):
         return [result.to_image_content()]
 
-    if isinstance(result, (list, tuple)):
-        return list(chain.from_iterable(_convert_to_content(item) for item in result))
+    if isinstance(result, list | tuple):
+        return list(chain.from_iterable(_convert_to_content(item) for item in result))  # type: ignore[reportUnknownVariableType]
 
     if not isinstance(result, str):
         try: