> ## Documentation Index > Fetch the complete documentation index at: https://gofastmcp.com/llms.txt > Use this file to discover all available pages before exploring further. # mcp_server_config # `fastmcp.utilities.mcp_server_config.v1.mcp_server_config` FastMCP Configuration File Support. This module provides support for fastmcp.json configuration files that allow users to specify server settings in a declarative format instead of using command-line arguments. ## Functions ### `generate_schema` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} generate_schema(output_path: Path | str | None = None) -> dict[str, Any] | None ``` Generate JSON schema for fastmcp.json files. This is used to create the schema file that IDEs can use for validation and auto-completion. **Args:** * `output_path`: Optional path to write the schema to. If provided, writes the schema and returns None. If not provided, returns the schema as a dictionary. **Returns:** * JSON schema as a dictionary if output\_path is None, otherwise None ## Classes ### `Deployment` Configuration for server deployment and runtime settings. **Methods:** #### `apply_runtime_settings` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} apply_runtime_settings(self, config_path: Path | None = None) -> None ``` Apply runtime settings like environment variables and working directory. **Args:** * `config_path`: Path to config file for resolving relative paths Environment variables support interpolation with ${VAR_NAME} syntax. For example: "API_URL": "https://api.${ENVIRONMENT}.example.com" will substitute the value of the ENVIRONMENT variable at runtime. ### `MCPServerConfig` Configuration for a FastMCP server. This configuration file allows you to specify all settings needed to run a FastMCP server in a declarative format. **Methods:** #### `validate_source` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} validate_source(cls, v: dict | Source) -> SourceType ``` Validate and convert source to proper format. Supports: * Dict format: `{"path": "server.py", "entrypoint": "app"}` * FileSystemSource instance (passed through) No string parsing happens here - that's only at CLI boundaries. MCPServerConfig works only with properly typed objects. #### `validate_environment` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} validate_environment(cls, v: dict | Any) -> EnvironmentType ``` Ensure environment has a type field for discrimination. For backward compatibility, if no type is specified, default to "uv". #### `validate_deployment` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} validate_deployment(cls, v: dict | Deployment) -> Deployment ``` Validate and convert deployment to Deployment. Accepts: * Deployment instance * dict that can be converted to Deployment #### `from_file` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} from_file(cls, file_path: Path) -> MCPServerConfig ``` Load configuration from a JSON file. **Args:** * `file_path`: Path to the configuration file **Returns:** * MCPServerConfig instance **Raises:** * `FileNotFoundError`: If the file doesn't exist * `json.JSONDecodeError`: If the file is not valid JSON * `pydantic.ValidationError`: If the configuration is invalid #### `from_cli_args` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} from_cli_args(cls, source: FileSystemSource, transport: Literal['stdio', 'http', 'sse', 'streamable-http'] | None = None, host: str | None = None, port: int | None = None, path: str | None = None, log_level: Literal['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'] | None = None, python: str | None = None, dependencies: list[str] | None = None, requirements: str | None = None, project: str | None = None, editable: str | None = None, env: dict[str, str] | None = None, cwd: str | None = None, args: list[str] | None = None) -> MCPServerConfig ``` Create a config from CLI arguments. This allows us to have a single code path where everything goes through a config object. **Args:** * `source`: Server source (FileSystemSource instance) * `transport`: Transport protocol * `host`: Host for HTTP transport * `port`: Port for HTTP transport * `path`: URL path for server * `log_level`: Logging level * `python`: Python version * `dependencies`: Python packages to install * `requirements`: Path to requirements file * `project`: Path to project directory * `editable`: Path to install in editable mode * `env`: Environment variables * `cwd`: Working directory * `args`: Server arguments **Returns:** * MCPServerConfig instance #### `find_config` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} find_config(cls, start_path: Path | None = None) -> Path | None ``` Find a fastmcp.json file in the specified directory. **Args:** * `start_path`: Directory to look in (defaults to current directory) **Returns:** * Path to the configuration file, or None if not found #### `prepare` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} prepare(self, skip_source: bool = False, output_dir: Path | None = None) -> None ``` Prepare environment and source for execution. When output\_dir is provided, creates a persistent uv project. When output\_dir is None, does ephemeral caching (for backwards compatibility). **Args:** * `skip_source`: Skip source preparation if True * `output_dir`: Directory to create the persistent uv project in (optional) #### `prepare_environment` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} prepare_environment(self, output_dir: Path | None = None) -> None ``` Prepare the Python environment. **Args:** * `output_dir`: If provided, creates a persistent uv project in this directory. If None, just populates uv's cache for ephemeral use. Delegates to the environment's prepare() method #### `prepare_source` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} prepare_source(self) -> None ``` Prepare the source for loading. Delegates to the source's prepare() method. #### `run_server` ```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}} run_server(self, **kwargs: Any) -> None ``` Load and run the server with this configuration. **Args:** * `**kwargs`: Additional arguments to pass to server.run\_async() These override config settings