from __future__ import annotations as _annotations
import inspect
import warnings
from pathlib import Path
from typing import Annotated, Any, Literal
from pydantic import Field, field_validator
from pydantic.fields import FieldInfo
from pydantic_settings import (
BaseSettings,
EnvSettingsSource,
PydanticBaseSettingsSource,
SettingsConfigDict,
)
from typing_extensions import Self
from fastmcp.utilities.logging import get_logger
logger = get_logger(__name__)
LOG_LEVEL = Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]
DuplicateBehavior = Literal["warn", "error", "replace", "ignore"]
class ExtendedEnvSettingsSource(EnvSettingsSource):
"""
A special EnvSettingsSource that allows for multiple env var prefixes to be used.
Raises a deprecation warning if the old `FASTMCP_SERVER_` prefix is used.
"""
def get_field_value(
self, field: FieldInfo, field_name: str
) -> tuple[Any, str, bool]:
if prefixes := self.config.get("env_prefixes"):
for prefix in prefixes:
self.env_prefix = prefix
env_val, field_key, value_is_complex = super().get_field_value(
field, field_name
)
if env_val is not None:
if prefix == "FASTMCP_SERVER_":
# Deprecated in 2.8.0
logger.warning(
"Using `FASTMCP_SERVER_` environment variables is deprecated. Use `FASTMCP_` instead.",
)
return env_val, field_key, value_is_complex
return super().get_field_value(field, field_name)
class ExtendedSettingsConfigDict(SettingsConfigDict, total=False):
env_prefixes: list[str] | None
class ExperimentalSettings(BaseSettings):
model_config = SettingsConfigDict(
env_prefix="FASTMCP_EXPERIMENTAL_",
extra="ignore",
)
enable_new_openapi_parser: Annotated[
bool,
Field(
description=inspect.cleandoc(
"""
Whether to use the new OpenAPI parser. This parser was introduced
for testing in 2.11 and will become the default soon.
"""
),
),
] = False
class Settings(BaseSettings):
"""FastMCP settings."""
model_config = ExtendedSettingsConfigDict(
env_prefixes=["FASTMCP_", "FASTMCP_SERVER_"],
env_file=".env",
extra="ignore",
env_nested_delimiter="__",
nested_model_default_partial_update=True,
validate_assignment=True,
)
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)
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)
@classmethod
def settings_customise_sources(
cls,
settings_cls: type[BaseSettings],
init_settings: PydanticBaseSettingsSource,
env_settings: PydanticBaseSettingsSource,
dotenv_settings: PydanticBaseSettingsSource,
file_secret_settings: PydanticBaseSettingsSource,
) -> tuple[PydanticBaseSettingsSource, ...]:
# can remove this classmethod after deprecated FASTMCP_SERVER_ prefix is
# removed
return (
init_settings,
ExtendedEnvSettingsSource(settings_cls),
dotenv_settings,
file_secret_settings,
)
@property
def settings(self) -> Self:
"""
This property is for backwards compatibility with FastMCP < 2.8.0,
which accessed fastmcp.settings.settings
"""
# Deprecated in 2.8.0
logger.warning(
"Using fastmcp.settings.settings is deprecated. Use fastmcp.settings instead.",
)
return self
home: Path = Path.home() / ".fastmcp"
test_mode: bool = False
log_level: LOG_LEVEL = "INFO"
@field_validator("log_level", mode="before")
@classmethod
def normalize_log_level(cls, v):
if isinstance(v, str):
return v.upper()
return v
experimental: ExperimentalSettings = ExperimentalSettings()
enable_rich_tracebacks: Annotated[
bool,
Field(
description=inspect.cleandoc(
"""
If True, will use rich tracebacks for logging.
"""
)
),
] = True
deprecation_warnings: Annotated[
bool,
Field(
description=inspect.cleandoc(
"""
Whether to show deprecation warnings. You can completely reset
Python's warning behavior by running `warnings.resetwarnings()`.
Note this will NOT apply to deprecation warnings from the
settings class itself.
""",
)
),
] = True
client_raise_first_exceptiongroup_error: Annotated[
bool,
Field(
default=True,
description=inspect.cleandoc(
"""
Many MCP components operate in anyio taskgroups, and raise
ExceptionGroups instead of exceptions. If this setting is True, FastMCP Clients
will `raise` the first error in any ExceptionGroup instead of raising
the ExceptionGroup as a whole. This is useful for debugging, but may
mask other errors.
"""
),
),
] = True
resource_prefix_format: Annotated[
Literal["protocol", "path"],
Field(
default="path",
description=inspect.cleandoc(
"""
When perfixing a resource URI, either use path formatting (resource://prefix/path)
or protocol formatting (prefix+resource://path). Protocol formatting was the default in FastMCP < 2.4;
path formatting is current default.
"""
),
),
] = "path"
client_init_timeout: Annotated[
float | None,
Field(
description="The timeout for the client's initialization handshake, in seconds. Set to None or 0 to disable.",
),
] = None
# HTTP settings
host: str = "127.0.0.1"
port: int = 8000
sse_path: str = "/sse"
message_path: str = "/messages/"
streamable_http_path: str = "/mcp"
debug: bool = False
# error handling
mask_error_details: Annotated[
bool,
Field(
default=False,
description=inspect.cleandoc(
"""
If True, error details from user-supplied functions (tool, resource, prompt)
will be masked before being sent to clients. Only error messages from explicitly
raised ToolError, ResourceError, or PromptError will be included in responses.
If False (default), all error details will be included in responses, but prefixed
with appropriate context.
"""
),
),
] = False
server_dependencies: list[str] = Field(
default_factory=list,
description="List of dependencies to install in the server environment",
)
# StreamableHTTP settings
json_response: bool = False
stateless_http: bool = (
False # If True, uses true stateless mode (new transport per request)
)
# Auth settings
server_auth: Annotated[
str | None,
Field(
description=inspect.cleandoc(
"""
Configure the authentication provider for the server. Auth
providers are registered with a specific key, and providing that
key here will cause the server to automatically configure the
provider from the environment.
If None, no automatic configuration will take place.
This setting is *always* overriden by any auth provider passed to the
FastMCP constructor.
Note that most auth providers require additional configuration
that must be provided via env vars.
"""
),
),
] = None
include_tags: Annotated[
set[str] | None,
Field(
default=None,
description=inspect.cleandoc(
"""
If provided, only components that match these tags will be
exposed to clients. A component is considered to match if ANY of
its tags match ANY of the tags in the set.
"""
),
),
] = None
exclude_tags: Annotated[
set[str] | None,
Field(
default=None,
description=inspect.cleandoc(
"""
If provided, components that match these tags will be excluded
from the server. A component is considered to match if ANY of
its tags match ANY of the tags in the set.
"""
),
),
] = None
include_fastmcp_meta: Annotated[
bool,
Field(
default=True,
description=inspect.cleandoc(
"""
Whether to include FastMCP meta in the server's MCP responses.
If True, a `_fastmcp` key will be added to the `meta` field of
all MCP component responses. This key will contain a dict of
various FastMCP-specific metadata, such as tags.
"""
),
),
] = True
def __getattr__(name: str):
"""
Used to deprecate the module-level Image class; can be removed once it is no longer imported to root.
"""
if name == "settings":
import fastmcp
settings = fastmcp.settings
# Deprecated in 2.10.2
if settings.deprecation_warnings:
warnings.warn(
"`from fastmcp.settings import settings` is deprecated. use `fastmcp.settings` instead.",
DeprecationWarning,
stacklevel=2,
)
return settings
raise AttributeError(f"module '{__name__}' has no attribute '{name}'")