Fix Server Creation with Auth Providers

src/fastmcp/prompts/prompt_manager.py

@@ -6,7 +6,7 @@ from typing import TYPE_CHECKING, Any
 
 from mcp import GetPromptResult
 
-from fastmcp import settings
+import fastmcp
 from fastmcp.exceptions import NotFoundError, PromptError
 from fastmcp.prompts.prompt import FunctionPrompt, Prompt, PromptResult
 from fastmcp.settings import DuplicateBehavior
@@ -28,7 +28,9 @@ class PromptManager:
     ):
         self._prompts: dict[str, Prompt] = {}
         self._mounted_servers: list[MountedServer] = []
-        self.mask_error_details = mask_error_details or settings.mask_error_details
+        self.mask_error_details = (
+            mask_error_details or fastmcp.settings.mask_error_details
+        )
 
         # Default to "warn" if None is provided
         if duplicate_behavior is None:
@@ -80,7 +82,7 @@ class PromptManager:
                 logger.warning(
                     f"Failed to get prompts from server: {mounted.server.name!r}, mounted at: {mounted.prefix!r}: {e}"
                 )
-                if settings.mounted_components_raise_on_load_error:
+                if fastmcp.settings.mounted_components_raise_on_load_error:
                     raise
                 continue
 
@@ -122,7 +124,7 @@ class PromptManager:
     ) -> FunctionPrompt:
         """Create a prompt from a function."""
         # deprecated in 2.7.0
-        if settings.deprecation_warnings:
+        if fastmcp.settings.deprecation_warnings:
             warnings.warn(
                 "PromptManager.add_prompt_from_fn() is deprecated. Use Prompt.from_function() and call add_prompt() instead.",
                 DeprecationWarning,

src/fastmcp/resources/resource_manager.py

@@ -9,7 +9,7 @@ from typing import TYPE_CHECKING, Any
 
 from pydantic import AnyUrl
 
-from fastmcp import settings
+import fastmcp
 from fastmcp.exceptions import NotFoundError, ResourceError
 from fastmcp.resources.resource import Resource
 from fastmcp.resources.template import (
@@ -44,7 +44,9 @@ class ResourceManager:
         self._resources: dict[str, Resource] = {}
         self._templates: dict[str, ResourceTemplate] = {}
         self._mounted_servers: list[MountedServer] = []
-        self.mask_error_details = mask_error_details or settings.mask_error_details
+        self.mask_error_details = (
+            mask_error_details or fastmcp.settings.mask_error_details
+        )
 
         # Default to "warn" if None is provided
         if duplicate_behavior is None:
@@ -114,7 +116,7 @@ class ResourceManager:
                 logger.warning(
                     f"Failed to get resources from server: {mounted.server.name!r}, mounted at: {mounted.prefix!r}: {e}"
                 )
-                if settings.mounted_components_raise_on_load_error:
+                if fastmcp.settings.mounted_components_raise_on_load_error:
                     raise
                 continue
 
@@ -167,7 +169,7 @@ class ResourceManager:
                 logger.warning(
                     f"Failed to get templates from server: {mounted.server.name!r}, mounted at: {mounted.prefix!r}: {e}"
                 )
-                if settings.mounted_components_raise_on_load_error:
+                if fastmcp.settings.mounted_components_raise_on_load_error:
                     raise
                 continue
 
@@ -261,7 +263,7 @@ class ResourceManager:
             returns the existing resource.
         """
         # deprecated in 2.7.0
-        if settings.deprecation_warnings:
+        if fastmcp.settings.deprecation_warnings:
             warnings.warn(
                 "add_resource_from_fn is deprecated. Use Resource.from_function() and call add_resource() instead.",
                 DeprecationWarning,
@@ -310,7 +312,7 @@ class ResourceManager:
     ) -> ResourceTemplate:
         """Create a template from a function."""
         # deprecated in 2.7.0
-        if settings.deprecation_warnings:
+        if fastmcp.settings.deprecation_warnings:
             warnings.warn(
                 "add_template_from_fn is deprecated. Use ResourceTemplate.from_function() and call add_template() instead.",
                 DeprecationWarning,

src/fastmcp/settings.py

@@ -86,31 +86,38 @@ class Settings(BaseSettings):
         validate_assignment=True,
     )
 
+    def _find_setting_level(self, attr: str) -> Any:
+        """
+        Get the parent of a setting. If the setting contains one or more `__`, it will be
+        treated as a nested setting.
+        """
+        current_settings_level = self
+
+        while "__" in attr:
+            parent_attr, attr = attr.split("__", 1)
+            if not hasattr(current_settings_level, parent_attr):
+                raise AttributeError(f"Setting {parent_attr} does not exist.")
+
+            # Go one level deeper into the nested settings
+            current_settings_level = getattr(current_settings_level, parent_attr)
+
+        return current_settings_level
+
     def get_setting(self, attr: str) -> Any:
         """
         Get a setting. If the setting contains one or more `__`, it will be
         treated as a nested setting.
         """
-        settings = self
-        while "__" in attr:
-            parent_attr, attr = attr.split("__", 1)
-            if not hasattr(settings, parent_attr):
-                raise AttributeError(f"Setting {parent_attr} does not exist.")
-            settings = getattr(settings, parent_attr)
-        return getattr(settings, attr)
+        settings_level = self._find_setting_level(attr)
+        return getattr(settings_level, attr)
 
     def set_setting(self, attr: str, value: Any) -> None:
         """
         Set a setting. If the setting contains one or more `__`, it will be
         treated as a nested setting.
         """
-        settings = self
-        while "__" in attr:
-            parent_attr, attr = attr.split("__", 1)
-            if not hasattr(settings, parent_attr):
-                raise AttributeError(f"Setting {parent_attr} does not exist.")
-            settings = getattr(settings, parent_attr)
-        setattr(settings, attr, value)
+        settings_level = self._find_setting_level(attr)
+        setattr(settings_level, attr, value)
 
     @classmethod
     def settings_customise_sources(

src/fastmcp/tools/tool_manager.py

@@ -6,7 +6,7 @@ from typing import TYPE_CHECKING, Any
 
 from mcp.types import ToolAnnotations
 
-from fastmcp import settings
+import fastmcp
 from fastmcp.exceptions import NotFoundError, ToolError
 from fastmcp.settings import DuplicateBehavior
 from fastmcp.tools.tool import Tool, ToolResult
@@ -33,7 +33,9 @@ class ToolManager:
     ):
         self._tools: dict[str, Tool] = {}
         self._mounted_servers: list[MountedServer] = []
-        self.mask_error_details = mask_error_details or settings.mask_error_details
+        self.mask_error_details = (
+            mask_error_details or fastmcp.settings.mask_error_details
+        )
         self.transformations = transformations or {}
 
         # Default to "warn" if None is provided
@@ -86,7 +88,7 @@ class ToolManager:
                 logger.warning(
                     f"Failed to get tools from server: {mounted.server.name!r}, mounted at: {mounted.prefix!r}: {e}"
                 )
-                if settings.mounted_components_raise_on_load_error:
+                if fastmcp.settings.mounted_components_raise_on_load_error:
                     raise
                 continue
 
@@ -146,7 +148,7 @@ class ToolManager:
     ) -> Tool:
         """Add a tool to the server."""
         # deprecated in 2.7.0
-        if settings.deprecation_warnings:
+        if fastmcp.settings.deprecation_warnings:
             warnings.warn(
                 "ToolManager.add_tool_from_fn() is deprecated. Use Tool.from_function() and call add_tool() instead.",
                 DeprecationWarning,

tests/deprecated/test_settings.py

@@ -1,10 +1,15 @@
 import os
 import warnings
+from pathlib import Path
+from tempfile import TemporaryDirectory
+from textwrap import dedent
 from unittest.mock import patch
 
 import pytest
 
 from fastmcp import FastMCP
+from fastmcp.client import Client
+from fastmcp.client.transports import PythonStdioTransport
 from fastmcp.settings import Settings
 from fastmcp.utilities.tests import caplog_for_fastmcp
 
@@ -12,6 +17,45 @@ from fastmcp.utilities.tests import caplog_for_fastmcp
 pytestmark = pytest.mark.filterwarnings("default::DeprecationWarning")
 
 
+class TestSettingsImport:
+    """Test settings import."""
+
+    async def test_settings_from_environment_issue_1749(self):
+        """Test that when auth is enabled, the server starts."""
+
+        script = dedent("""
+        import os
+
+        os.environ["FASTMCP_SERVER_AUTH"] = "fastmcp.server.auth.providers.azure.AzureProvider"
+
+        os.environ["FASTMCP_SERVER_AUTH_AZURE_TENANT_ID"] = "A_Valid_Value"
+        os.environ["FASTMCP_SERVER_AUTH_AZURE_CLIENT_ID"] = "A_Valid_Value"
+        os.environ["FASTMCP_SERVER_AUTH_AZURE_CLIENT_SECRET"] = "A_Valid_Value"
+        os.environ["FASTMCP_SERVER_AUTH_AZURE_REDIRECT_PATH"] = "/auth/callback"
+        os.environ["FASTMCP_SERVER_AUTH_AZURE_BASE_URL"] = "http://localhost:8000"
+        os.environ["FASTMCP_SERVER_AUTH_AZURE_REQUIRED_SCOPES"] = "User.Read,email,profile"
+
+        import fastmcp
+        
+        mcp = fastmcp.FastMCP("TestServer")
+
+        mcp.run()
+        """)
+
+        with TemporaryDirectory() as temp_dir:
+            server_file = Path(temp_dir) / "server.py"
+            server_file.write_text(script)
+
+            transport: PythonStdioTransport = PythonStdioTransport(
+                script_path=server_file
+            )
+
+            async with Client[PythonStdioTransport](transport=transport) as client:
+                tools = await client.list_tools()
+
+                assert tools == []
+
+
 class TestDeprecatedServerInitKwargs:
     """Test deprecated server initialization keyword arguments."""