use type

examples/mount_example.py

@@ -9,7 +9,6 @@ the ToolManager's import_tools functionality. It shows how to:
 """
 
 import asyncio
-from typing import Dict, List
 
 from fastmcp import FastMCP
 
@@ -34,7 +33,7 @@ news_app = FastMCP("News App")
 
 
 @news_app.tool()
-def get_news_headlines() -> List[str]:
+def get_news_headlines() -> list[str]:
     """Get the latest news headlines."""
     return [
         "Tech company launches new product",
@@ -58,7 +57,7 @@ app = FastMCP("Main App")
 
 
 @app.tool()
-def check_app_status() -> Dict[str, str]:
+def check_app_status() -> dict[str, str]:
     """Check the status of the main application."""
     return {"status": "running", "version": "1.0.0", "uptime": "3h 24m"}
 

src/fastmcp/client/client.py

@@ -1,6 +1,7 @@
 import datetime
+from contextlib import AbstractAsyncContextManager
 from pathlib import Path
-from typing import Any, AsyncContextManager
+from typing import Any
 
 import mcp.types
 from mcp import ClientSession
@@ -48,7 +49,7 @@ class Client:
     ):
         self.transport = infer_transport(transport)
         self._session: ClientSession | None = None
-        self._session_cm: AsyncContextManager[ClientSession] | None = None
+        self._session_cm: AbstractAsyncContextManager[ClientSession] | None = None
 
         # Store common kwargs to pass to transport.connect_session
         if roots is not None and list_roots_callback is not None:

src/fastmcp/client/transports.py

@@ -2,14 +2,10 @@ import abc
 import contextlib
 import datetime
 import os
+from collections.abc import AsyncIterator
 from pathlib import Path
 from typing import (
-    AsyncIterator,
-    Dict,
-    List,
-    Optional,
     TypedDict,
-    Union,
 )
 
 from mcp import ClientSession, StdioServerParameters
@@ -103,7 +99,7 @@ class WSTransport(ClientTransport):
 class SSETransport(ClientTransport):
     """Transport implementation that connects to an MCP server via Server-Sent Events."""
 
-    def __init__(self, url: str | AnyUrl, headers: Optional[Dict[str, str]] = None):
+    def __init__(self, url: str | AnyUrl, headers: dict[str, str] | None = None):
         if isinstance(url, AnyUrl):
             url = str(url)
         if not isinstance(url, str) or not url.startswith("http"):
@@ -138,9 +134,9 @@ class StdioTransport(ClientTransport):
     def __init__(
         self,
         command: str,
-        args: List[str],
-        env: Optional[Dict[str, str]] = None,
-        cwd: Optional[str] = None,
+        args: list[str],
+        env: dict[str, str] | None = None,
+        cwd: str | None = None,
     ):
         """
         Initialize a Stdio transport.
@@ -182,10 +178,10 @@ class PythonStdioTransport(StdioTransport):
 
     def __init__(
         self,
-        script_path: Union[str, Path],
-        args: Optional[List[str]] = None,
-        env: Optional[Dict[str, str]] = None,
-        cwd: Optional[str] = None,
+        script_path: str | Path,
+        args: list[str] | None = None,
+        env: dict[str, str] | None = None,
+        cwd: str | None = None,
         python_cmd: str = "python",
     ):
         """
@@ -217,10 +213,10 @@ class NodeStdioTransport(StdioTransport):
 
     def __init__(
         self,
-        script_path: Union[str, Path],
-        args: Optional[List[str]] = None,
-        env: Optional[Dict[str, str]] = None,
-        cwd: Optional[str] = None,
+        script_path: str | Path,
+        args: list[str] | None = None,
+        env: dict[str, str] | None = None,
+        cwd: str | None = None,
         node_cmd: str = "node",
     ):
         """
@@ -253,12 +249,12 @@ class UvxStdioTransport(StdioTransport):
     def __init__(
         self,
         tool_name: str,
-        tool_args: Optional[List[str]] = None,
-        project_directory: Optional[str] = None,
-        python_version: Optional[str] = None,
-        with_packages: Optional[List[str]] = None,
-        from_package: Optional[str] = None,
-        env_vars: Optional[Dict[str, str]] = None,
+        tool_args: list[str] | None = None,
+        project_directory: str | None = None,
+        python_version: str | None = None,
+        with_packages: list[str] | None = None,
+        from_package: str | None = None,
+        env_vars: dict[str, str] | None = None,
     ):
         """
         Initialize a Uvx transport.
@@ -308,9 +304,9 @@ class NpxStdioTransport(StdioTransport):
     def __init__(
         self,
         package: str,
-        args: Optional[List[str]] = None,
-        project_directory: Optional[str] = None,
-        env_vars: Optional[Dict[str, str]] = None,
+        args: list[str] | None = None,
+        project_directory: str | None = None,
+        env_vars: dict[str, str] | None = None,
         use_package_lock: bool = True,
     ):
         """
@@ -394,7 +390,7 @@ def infer_transport(
         return FastMCPTransport(mcp=transport)
 
     # the transport is a path to a script
-    elif isinstance(transport, (Path, str)) and Path(transport).exists():
+    elif isinstance(transport, Path | str) and Path(transport).exists():
         if str(transport).endswith(".py"):
             return PythonStdioTransport(script_path=transport)
         elif str(transport).endswith(".js"):
@@ -403,11 +399,11 @@ def infer_transport(
             raise ValueError(f"Unsupported script type: {transport}")
 
     # the transport is an http(s) URL
-    elif isinstance(transport, (AnyUrl, str)) and str(transport).startswith("http"):
+    elif isinstance(transport, AnyUrl | str) and str(transport).startswith("http"):
         return SSETransport(url=transport)
 
     # the transport is a websocket URL
-    elif isinstance(transport, (AnyUrl, str)) and str(transport).startswith("ws"):
+    elif isinstance(transport, AnyUrl | str) and str(transport).startswith("ws"):
         return WSTransport(url=transport)
 
     # the transport is an unknown type

src/fastmcp/server/openapi.py

@@ -4,7 +4,8 @@ import enum
 import json
 import re
 from dataclasses import dataclass
-from typing import Any, Literal, Pattern
+from re import Pattern
+from typing import Any, Literal
 
 import httpx
 from pydantic.networks import AnyUrl

src/fastmcp/server/server.py

@@ -100,7 +100,7 @@ class FastMCP(Generic[LifespanResultT]):
         self.dependencies = self.settings.dependencies
 
         # Setup for mounted apps
-        self._mounted_apps: dict[str, "FastMCP"] = {}
+        self._mounted_apps: dict[str, FastMCP] = {}
 
         # Set up MCP protocol handlers
         self._setup_handlers()

src/fastmcp/tools/tool_manager.py

@@ -62,7 +62,7 @@ class ToolManager:
         return await tool.run(arguments, context=context)
 
     def import_tools(
-        self, tool_manager: "ToolManager", prefix: str | None = None
+        self, tool_manager: ToolManager, prefix: str | None = None
     ) -> None:
         """
         Import all tools from another ToolManager with prefixed names.

tests/utilities/openapi/test_openapi.py

@@ -1,6 +1,6 @@
 """Tests for the OpenAPI parsing utilities."""
 
-from typing import Any, Dict
+from typing import Any
 
 import pytest
 from fastapi import Body, FastAPI, Path, Query
@@ -12,7 +12,7 @@ from fastmcp.utilities.openapi import parse_openapi_to_http_routes
 
 
 @pytest.fixture
-def petstore_schema() -> Dict[str, Any]:
+def petstore_schema() -> dict[str, Any]:
     """Fixture that returns a simple Pet Store API schema."""
     return {
         "openapi": "3.1.0",
@@ -109,7 +109,7 @@ def parsed_petstore_routes(petstore_schema):
 
 
 @pytest.fixture
-def bookstore_schema() -> Dict[str, Any]:
+def bookstore_schema() -> dict[str, Any]:
     """Fixture that returns a Book Store API schema with different parameter types."""
     return {
         "openapi": "3.1.0",
@@ -292,7 +292,7 @@ def fastapi_app() -> FastAPI:
 
 
 @pytest.fixture
-def fastapi_openapi_schema(fastapi_app) -> Dict[str, Any]:
+def fastapi_openapi_schema(fastapi_app) -> dict[str, Any]:
     """Fixture that returns the OpenAPI schema of the FastAPI app."""
     return fastapi_app.openapi()
 

tests/utilities/openapi/test_openapi_advanced.py

@@ -1,6 +1,6 @@
 """Tests for advanced features of the OpenAPI utilities."""
 
-from typing import Any, Dict
+from typing import Any
 
 import pytest
 
@@ -8,7 +8,7 @@ from fastmcp.utilities.openapi import parse_openapi_to_http_routes
 
 
 @pytest.fixture
-def complex_schema() -> Dict[str, Any]:
+def complex_schema() -> dict[str, Any]:
     """Fixture that returns a complex OpenAPI schema with nested references."""
     return {
         "openapi": "3.1.0",
@@ -167,7 +167,7 @@ def complex_route_map(parsed_complex_routes):
 
 
 @pytest.fixture
-def schema_with_invalid_reference() -> Dict[str, Any]:
+def schema_with_invalid_reference() -> dict[str, Any]:
     """Fixture that returns a schema with an invalid reference."""
     return {
         "openapi": "3.1.0",
@@ -191,7 +191,7 @@ def schema_with_invalid_reference() -> Dict[str, Any]:
 
 
 @pytest.fixture
-def schema_with_content_params() -> Dict[str, Any]:
+def schema_with_content_params() -> dict[str, Any]:
     """Fixture that returns a schema with content-based parameters (complex parameters)."""
     return {
         "openapi": "3.1.0",
@@ -236,7 +236,7 @@ def parsed_content_param_routes(schema_with_content_params):
 
 
 @pytest.fixture
-def schema_all_http_methods() -> Dict[str, Any]:
+def schema_all_http_methods() -> dict[str, Any]:
     """Fixture that returns a schema with all HTTP methods."""
     return {
         "openapi": "3.1.0",

tests/utilities/openapi/test_openapi_fastapi.py

@@ -1,6 +1,6 @@
 """Tests for FastAPI integration with the OpenAPI utilities."""
 
-from typing import Any, Dict
+from typing import Any
 
 import pytest
 from fastapi import FastAPI
@@ -12,7 +12,6 @@ from fastmcp.utilities.openapi import parse_openapi_to_http_routes
 def fastapi_server() -> FastAPI:
     """Fixture that returns a FastAPI app for live OpenAPI schema testing."""
     from enum import Enum
-    from typing import List
 
     from fastapi import Body, Depends, Header, HTTPException, Path, Query
     from pydantic import BaseModel, Field
@@ -145,7 +144,7 @@ def fastapi_server() -> FastAPI:
     )
     async def update_item_tags(
         item_id: int = Path(..., description="The ID of the item"),
-        tags: List[str] = Body(..., description="Updated tags"),
+        tags: list[str] = Body(..., description="Updated tags"),
     ):
         """Update just the tags of an item."""
         return {"item_id": item_id, "tags": tags}
@@ -229,7 +228,7 @@ def fastapi_server() -> FastAPI:
 
 
 @pytest.fixture
-def fastapi_openapi_schema(fastapi_server) -> Dict[str, Any]:
+def fastapi_openapi_schema(fastapi_server) -> dict[str, Any]:
     """Fixture that returns the OpenAPI schema from a live FastAPI server."""
     return fastapi_server.openapi()