server.py

"""MCPServer - A more ergonomic interface for MCP servers."""

from __future__ import annotations

import base64
import inspect
import json
import re
from collections.abc import AsyncIterator, Awaitable, Callable, Iterable, Sequence
from contextlib import AbstractAsyncContextManager, asynccontextmanager
from typing import Any, Generic, Literal, TypeVar, overload

import anyio
import pydantic_core
from pydantic.networks import AnyUrl
from pydantic_settings import BaseSettings, SettingsConfigDict
from starlette.applications import Starlette
from starlette.middleware import Middleware
from starlette.middleware.authentication import AuthenticationMiddleware
from starlette.requests import Request
from starlette.responses import Response
from starlette.routing import Mount, Route
from starlette.types import Receive, Scope, Send

from mcp.server.auth.middleware.auth_context import AuthContextMiddleware
from mcp.server.auth.middleware.bearer_auth import BearerAuthBackend, RequireAuthMiddleware
from mcp.server.auth.provider import OAuthAuthorizationServerProvider, ProviderTokenVerifier, TokenVerifier
from mcp.server.auth.settings import AuthSettings
from mcp.server.context import ServerRequestContext
from mcp.server.lowlevel.helper_types import ReadResourceContents
from mcp.server.lowlevel.server import LifespanResultT, Server
from mcp.server.lowlevel.server import lifespan as default_lifespan
from mcp.server.mcpserver.context import Context
from mcp.server.mcpserver.exceptions import PromptError, ResourceError, ToolError
from mcp.server.mcpserver.prompts import Prompt, PromptManager
from mcp.server.mcpserver.resources import FunctionResource, Resource, ResourceManager
from mcp.server.mcpserver.tools import Tool, ToolManager
from mcp.server.mcpserver.utilities.context_injection import find_context_parameter
from mcp.server.mcpserver.utilities.logging import configure_logging, get_logger
from mcp.server.sse import SseServerTransport
from mcp.server.stdio import stdio_server
from mcp.server.streamable_http import EventStore
from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
from mcp.server.transport_security import TransportSecuritySettings
from mcp.shared.exceptions import MCPError
from mcp.types import (
    INTERNAL_ERROR,
    INVALID_PARAMS,
    Annotations,
    BlobResourceContents,
    CallToolRequestParams,
    CallToolResult,
    CompleteRequestParams,
    CompleteResult,
    Completion,
    ContentBlock,
    GetPromptRequestParams,
    GetPromptResult,
    Icon,
    ListPromptsResult,
    ListResourcesResult,
    ListResourceTemplatesResult,
    ListToolsResult,
    PaginatedRequestParams,
    ReadResourceRequestParams,
    ReadResourceResult,
    TextContent,
    TextResourceContents,
    ToolAnnotations,
)
from mcp.types import Prompt as MCPPrompt
from mcp.types import PromptArgument as MCPPromptArgument
from mcp.types import Resource as MCPResource
from mcp.types import ResourceTemplate as MCPResourceTemplate
from mcp.types import Tool as MCPTool

logger = get_logger(__name__)

_CallableT = TypeVar("_CallableT", bound=Callable[..., Any])


class Settings(BaseSettings, Generic[LifespanResultT]):
    """MCPServer settings.

    All settings can be configured via environment variables with the prefix MCP_.
    For example, MCP_DEBUG=true will set debug=True.
    """

    model_config = SettingsConfigDict(
        env_prefix="MCP_",
        env_file=".env",
        env_nested_delimiter="__",
        nested_model_default_partial_update=True,
        extra="ignore",
    )

    # Server settings
    debug: bool
    log_level: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]

    # resource settings
    warn_on_duplicate_resources: bool

    # tool settings
    warn_on_duplicate_tools: bool

    # prompt settings
    warn_on_duplicate_prompts: bool

    lifespan: Callable[[MCPServer[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]] | None
    """An async context manager that will be called when the server is started."""

    auth: AuthSettings | None


def lifespan_wrapper(
    app: MCPServer[LifespanResultT],
    lifespan: Callable[[MCPServer[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]],
) -> Callable[[Server[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]]:
    @asynccontextmanager
    async def wrap(_: Server[LifespanResultT]) -> AsyncIterator[LifespanResultT]:
        async with lifespan(app) as context:
            yield context

    return wrap


class MCPServer(Generic[LifespanResultT]):
    def __init__(
        self,
        name: str | None = None,
        title: str | None = None,
        description: str | None = None,
        instructions: str | None = None,
        website_url: str | None = None,
        icons: list[Icon] | None = None,
        version: str | None = None,
        auth_server_provider: OAuthAuthorizationServerProvider[Any, Any, Any] | None = None,
        token_verifier: TokenVerifier | None = None,
        *,
        tools: list[Tool] | None = None,
        debug: bool = False,
        log_level: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"] = "INFO",
        warn_on_duplicate_resources: bool = True,
        warn_on_duplicate_tools: bool = True,
        warn_on_duplicate_prompts: bool = True,
        lifespan: Callable[[MCPServer[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]] | None = None,
        auth: AuthSettings | None = None,
    ):
        self.settings = Settings(
            debug=debug,
            log_level=log_level,
            warn_on_duplicate_resources=warn_on_duplicate_resources,
            warn_on_duplicate_tools=warn_on_duplicate_tools,
            warn_on_duplicate_prompts=warn_on_duplicate_prompts,
            lifespan=lifespan,
            auth=auth,
        )

        self._tool_manager = ToolManager(tools=tools, warn_on_duplicate_tools=self.settings.warn_on_duplicate_tools)
        self._resource_manager = ResourceManager(warn_on_duplicate_resources=self.settings.warn_on_duplicate_resources)
        self._prompt_manager = PromptManager(warn_on_duplicate_prompts=self.settings.warn_on_duplicate_prompts)
        self._lowlevel_server = Server(
            name=name or "mcp-server",
            title=title,
            description=description,
            instructions=instructions,
            website_url=website_url,
            icons=icons,
            version=version,
            on_list_tools=self._handle_list_tools,
            on_call_tool=self._handle_call_tool,
            on_list_resources=self._handle_list_resources,
            on_read_resource=self._handle_read_resource,
            on_list_resource_templates=self._handle_list_resource_templates,
            on_list_prompts=self._handle_list_prompts,
            on_get_prompt=self._handle_get_prompt,
            # TODO(Marcelo): It seems there's a type mismatch between the lifespan type from an MCPServer and Server.
            # We need to create a Lifespan type that is a generic on the server type, like Starlette does.
            lifespan=(lifespan_wrapper(self, self.settings.lifespan) if self.settings.lifespan else default_lifespan),  # type: ignore
        )
        # Validate auth configuration
        if self.settings.auth is not None:
            if auth_server_provider and token_verifier:  # pragma: no cover
                raise ValueError("Cannot specify both auth_server_provider and token_verifier")
            if not auth_server_provider and not token_verifier:  # pragma: no cover
                raise ValueError("Must specify either auth_server_provider or token_verifier when auth is enabled")
        elif auth_server_provider or token_verifier:  # pragma: no cover
            raise ValueError("Cannot specify auth_server_provider or token_verifier without auth settings")

        self._auth_server_provider = auth_server_provider
        self._token_verifier = token_verifier

        # Create token verifier from provider if needed (backwards compatibility)
        if auth_server_provider and not token_verifier:  # pragma: no cover
            self._token_verifier = ProviderTokenVerifier(auth_server_provider)
        self._custom_starlette_routes: list[Route] = []

        # Configure logging
        configure_logging(self.settings.log_level)

    @property
    def name(self) -> str:
        return self._lowlevel_server.name

    @property
    def title(self) -> str | None:
        return self._lowlevel_server.title

    @property
    def description(self) -> str | None:
        return self._lowlevel_server.description

    @property
    def instructions(self) -> str | None:
        return self._lowlevel_server.instructions

    @property
    def website_url(self) -> str | None:
        return self._lowlevel_server.website_url

    @property
    def icons(self) -> list[Icon] | None:
        return self._lowlevel_server.icons

    @property
    def version(self) -> str | None:
        return self._lowlevel_server.version

    @property
    def session_manager(self) -> StreamableHTTPSessionManager:
        """Get the StreamableHTTP session manager.

        This is exposed to enable advanced use cases like mounting multiple
        MCPServer instances in a single FastAPI application.

        Raises:
            RuntimeError: If called before streamable_http_app() has been called.
        """
        return self._lowlevel_server.session_manager  # pragma: no cover

    @overload
    def run(self, transport: Literal["stdio"] = ...) -> None: ...

    @overload
    def run(
        self,
        transport: Literal["sse"],
        *,
        host: str = ...,
        port: int = ...,
        sse_path: str = ...,
        message_path: str = ...,
        transport_security: TransportSecuritySettings | None = ...,
    ) -> None: ...

    @overload
    def run(
        self,
        transport: Literal["streamable-http"],
        *,
        host: str = ...,
        port: int = ...,
        streamable_http_path: str = ...,
        json_response: bool = ...,
        stateless_http: bool = ...,
        event_store: EventStore | None = ...,
        retry_interval: int | None = ...,
        transport_security: TransportSecuritySettings | None = ...,
    ) -> None: ...

    def run(
        self,
        transport: Literal["stdio", "sse", "streamable-http"] = "stdio",
        **kwargs: Any,
    ) -> None:
        """Run the MCP server. Note this is a synchronous function.

        Args:
            transport: Transport protocol to use ("stdio", "sse", or "streamable-http")
            **kwargs: Transport-specific options (see overloads for details)
        """
        TRANSPORTS = Literal["stdio", "sse", "streamable-http"]
        if transport not in TRANSPORTS.__args__:  # type: ignore  # pragma: no cover
            raise ValueError(f"Unknown transport: {transport}")

        match transport:
            case "stdio":
                anyio.run(self.run_stdio_async)
            case "sse":  # pragma: no cover
                anyio.run(lambda: self.run_sse_async(**kwargs))
            case "streamable-http":  # pragma: no cover
                anyio.run(lambda: self.run_streamable_http_async(**kwargs))

    async def _handle_list_tools(
        self, ctx: ServerRequestContext[LifespanResultT], params: PaginatedRequestParams | None
    ) -> ListToolsResult:
        return ListToolsResult(tools=await self.list_tools())

    async def _handle_call_tool(
        self, ctx: ServerRequestContext[LifespanResultT], params: CallToolRequestParams
    ) -> CallToolResult:
        context = Context(request_context=ctx, mcp_server=self)
        try:
            result = await self.call_tool(params.name, params.arguments or {}, context)
        except MCPError:
            raise
        except ToolError as e:
            return CallToolResult(content=[TextContent(type="text", text=str(e))], is_error=True)
        except Exception:
            logger.exception(f"Unhandled error in tool {params.name}")
            return CallToolResult(
                content=[TextContent(type="text", text=f"Internal error executing tool {params.name}")],
                is_error=True,
            )
        if isinstance(result, CallToolResult):
            return result
        if isinstance(result, tuple) and len(result) == 2:
            unstructured_content, structured_content = result
            return CallToolResult(
                content=list(unstructured_content),  # type: ignore[arg-type]
                structured_content=structured_content,  # type: ignore[arg-type]
            )
        if isinstance(result, dict):  # pragma: no cover
            # TODO: this code path is unreachable — convert_result never returns a raw dict.
            # The call_tool return type (Sequence[ContentBlock] | dict[str, Any]) is wrong
            # and needs to be cleaned up.
            return CallToolResult(
                content=[TextContent(type="text", text=json.dumps(result, indent=2))],
                structured_content=result,
            )
        return CallToolResult(content=list(result))

    async def _handle_list_resources(
        self, ctx: ServerRequestContext[LifespanResultT], params: PaginatedRequestParams | None
    ) -> ListResourcesResult:
        return ListResourcesResult(resources=await self.list_resources())

    async def _handle_read_resource(
        self, ctx: ServerRequestContext[LifespanResultT], params: ReadResourceRequestParams
    ) -> ReadResourceResult:
        context = Context(request_context=ctx, mcp_server=self)
        try:
            results = await self.read_resource(params.uri, context)
        except MCPError:
            raise
        except ResourceError as e:
            raise MCPError(code=INVALID_PARAMS, message=str(e))
        except Exception:
            logger.exception(f"Unhandled error reading resource {params.uri}")
            raise MCPError(code=INTERNAL_ERROR, message=f"Internal error reading resource {params.uri}")

        contents: list[TextResourceContents | BlobResourceContents] = []
        for item in results:
            if isinstance(item.content, bytes):
                contents.append(
                    BlobResourceContents(
                        uri=params.uri,
                        blob=base64.b64encode(item.content).decode(),
                        mime_type=item.mime_type or "application/octet-stream",
                        _meta=item.meta,
                    )
                )
            else:
                contents.append(
                    TextResourceContents(
                        uri=params.uri,
                        text=item.content,
                        mime_type=item.mime_type or "text/plain",
                        _meta=item.meta,
                    )
                )
        return ReadResourceResult(contents=contents)

    async def _handle_list_resource_templates(
        self, ctx: ServerRequestContext[LifespanResultT], params: PaginatedRequestParams | None
    ) -> ListResourceTemplatesResult:
        return ListResourceTemplatesResult(resource_templates=await self.list_resource_templates())

    async def _handle_list_prompts(
        self, ctx: ServerRequestContext[LifespanResultT], params: PaginatedRequestParams | None
    ) -> ListPromptsResult:
        return ListPromptsResult(prompts=await self.list_prompts())

    async def _handle_get_prompt(
        self, ctx: ServerRequestContext[LifespanResultT], params: GetPromptRequestParams
    ) -> GetPromptResult:
        context = Context(request_context=ctx, mcp_server=self)
        try:
            return await self.get_prompt(params.name, params.arguments, context)
        except MCPError:
            raise
        except PromptError as e:
            raise MCPError(code=INVALID_PARAMS, message=str(e))
        except Exception:
            logger.exception(f"Unhandled error in prompt {params.name}")
            raise MCPError(code=INTERNAL_ERROR, message=f"Internal error getting prompt {params.name}")

    async def list_tools(self) -> list[MCPTool]:
        """List all available tools."""
        tools = self._tool_manager.list_tools()
        return [
            MCPTool(
                name=info.name,
                title=info.title,
                description=info.description,
                input_schema=info.parameters,
                output_schema=info.output_schema,
                annotations=info.annotations,
                icons=info.icons,
                _meta=info.meta,
            )
            for info in tools
        ]

    async def call_tool(
        self, name: str, arguments: dict[str, Any], context: Context[LifespanResultT, Any] | None = None
    ) -> Sequence[ContentBlock] | dict[str, Any]:
        """Call a tool by name with arguments."""
        if context is None:
            context = Context(mcp_server=self)
        return await self._tool_manager.call_tool(name, arguments, context, convert_result=True)

    async def list_resources(self) -> list[MCPResource]:
        """List all available resources."""

        resources = self._resource_manager.list_resources()
        return [
            MCPResource(
                uri=resource.uri,
                name=resource.name or "",
                title=resource.title,
                description=resource.description,
                mime_type=resource.mime_type,
                icons=resource.icons,
                annotations=resource.annotations,
                _meta=resource.meta,
            )
            for resource in resources
        ]

    async def list_resource_templates(self) -> list[MCPResourceTemplate]:
        templates = self._resource_manager.list_templates()
        return [
            MCPResourceTemplate(
                uri_template=template.uri_template,
                name=template.name,
                title=template.title,
                description=template.description,
                mime_type=template.mime_type,
                icons=template.icons,
                annotations=template.annotations,
                _meta=template.meta,
            )
            for template in templates
        ]

    async def read_resource(
        self, uri: AnyUrl | str, context: Context[LifespanResultT, Any] | None = None
    ) -> Iterable[ReadResourceContents]:
        """Read a resource by URI."""
        if context is None:
            context = Context(mcp_server=self)
        try:
            resource = await self._resource_manager.get_resource(uri, context)
        except ValueError:
            raise ResourceError(f"Unknown resource: {uri}")

        try:
            content = await resource.read()
            return [ReadResourceContents(content=content, mime_type=resource.mime_type, meta=resource.meta)]
        except (ResourceError, MCPError):
            raise
        except Exception as exc:
            logger.exception(f"Error reading resource {uri}")
            raise ResourceError(f"Error reading resource {uri}") from exc

    def add_tool(
        self,
        fn: Callable[..., Any],
        name: str | None = None,
        title: str | None = None,
        description: str | None = None,
        annotations: ToolAnnotations | None = None,
        icons: list[Icon] | None = None,
        meta: dict[str, Any] | None = None,
        structured_output: bool | None = None,
    ) -> None:
        """Add a tool to the server.

        The tool function can optionally request a Context object by adding a parameter
        with the Context type annotation. See the @tool decorator for examples.

        Args:
            fn: The function to register as a tool
            name: Optional name for the tool (defaults to function name)
            title: Optional human-readable title for the tool
            description: Optional description of what the tool does
            annotations: Optional ToolAnnotations providing additional tool information
            icons: Optional list of icons for the tool
            meta: Optional metadata dictionary for the tool
            structured_output: Controls whether the tool's output is structured or unstructured
                - If None, auto-detects based on the function's return type annotation
                - If True, creates a structured tool (return type annotation permitting)
                - If False, unconditionally creates an unstructured tool
        """
        self._tool_manager.add_tool(
            fn,
            name=name,
            title=title,
            description=description,
            annotations=annotations,
            icons=icons,
            meta=meta,
            structured_output=structured_output,
        )

    def remove_tool(self, name: str) -> None:
        """Remove a tool from the server by name.

        Args:
            name: The name of the tool to remove

        Raises:
            ToolError: If the tool does not exist
        """
        self._tool_manager.remove_tool(name)

    def tool(
        self,
        name: str | None = None,
        title: str | None = None,
        description: str | None = None,
        annotations: ToolAnnotations | None = None,
        icons: list[Icon] | None = None,
        meta: dict[str, Any] | None = None,
        structured_output: bool | None = None,
    ) -> Callable[[_CallableT], _CallableT]:
        """Decorator to register a tool.

        Tools can optionally request a Context object by adding a parameter with the
        Context type annotation. The context provides access to MCP capabilities like
        logging, progress reporting, and resource access.

        Args:
            name: Optional name for the tool (defaults to function name)
            title: Optional human-readable title for the tool
            description: Optional description of what the tool does
            annotations: Optional ToolAnnotations providing additional tool information
            icons: Optional list of icons for the tool
            meta: Optional metadata dictionary for the tool
            structured_output: Controls whether the tool's output is structured or unstructured
                - If None, auto-detects based on the function's return type annotation
                - If True, creates a structured tool (return type annotation permitting)
                - If False, unconditionally creates an unstructured tool

        Example:
            ```python
            @server.tool()
            def my_tool(x: int) -> str:
                return str(x)
            ```

            ```python
            @server.tool()
            async def tool_with_context(x: int, ctx: Context) -> str:
                await ctx.info(f"Processing {x}")
                return str(x)
            ```

            ```python
            @server.tool()
            async def async_tool(x: int, context: Context) -> str:
                await context.report_progress(50, 100)
                return str(x)
            ```
        """
        # Check if user passed function directly instead of calling decorator
        if callable(name):
            raise TypeError(
                "The @tool decorator was used incorrectly. Did you forget to call it? Use @tool() instead of @tool"
            )

        def decorator(fn: _CallableT) -> _CallableT:
            self.add_tool(
                fn,
                name=name,
                title=title,
                description=description,
                annotations=annotations,
                icons=icons,
                meta=meta,
                structured_output=structured_output,
            )
            return fn

        return decorator

    def completion(self):
        """Decorator to register a completion handler.

        The completion handler receives:
        - ref: PromptReference or ResourceTemplateReference
        - argument: CompletionArgument with name and partial value
        - context: Optional CompletionContext with previously resolved arguments

        Example:
            ```python
            @mcp.completion()
            async def handle_completion(ref, argument, context):
                if isinstance(ref, ResourceTemplateReference):
                    # Return completions based on ref, argument, and context
                    return Completion(values=["option1", "option2"])
                return None
            ```
        """

        def decorator(func: _CallableT) -> _CallableT:
            async def handler(
                ctx: ServerRequestContext[LifespanResultT], params: CompleteRequestParams
            ) -> CompleteResult:
                result = await func(params.ref, params.argument, params.context)
                return CompleteResult(
                    completion=result if result is not None else Completion(values=[], total=None, has_more=None),
                )

            # TODO(maxisbey): remove private access — completion needs post-construction
            #   handler registration, find a better pattern for this
            self._lowlevel_server._add_request_handler(  # pyright: ignore[reportPrivateUsage]
                "completion/complete", handler
            )
            return func

        return decorator

    def add_resource(self, resource: Resource) -> None:
        """Add a resource to the server.

        Args:
            resource: A Resource instance to add
        """
        self._resource_manager.add_resource(resource)

    def resource(
        self,
        uri: str,
        *,
        name: str | None = None,
        title: str | None = None,
        description: str | None = None,
        mime_type: str | None = None,
        icons: list[Icon] | None = None,
        annotations: Annotations | None = None,
        meta: dict[str, Any] | None = None,
    ) -> Callable[[_CallableT], _CallableT]:
        """Decorator to register a function as a resource.

        The function will be called when the resource is read to generate its content.
        The function can return:
        - str for text content
        - bytes for binary content
        - other types will be converted to JSON

        If the URI contains parameters (e.g. "resource://{param}") or the function
        has parameters, it will be registered as a template resource.

        Args:
            uri: URI for the resource (e.g. "resource://my-resource" or "resource://{param}")
            name: Optional name for the resource
            title: Optional human-readable title for the resource
            description: Optional description of the resource
            mime_type: Optional MIME type for the resource
            icons: Optional list of icons for the resource
            annotations: Optional annotations for the resource
            meta: Optional metadata dictionary for the resource

        Example:
            ```python
            @server.resource("resource://my-resource")
            def get_data() -> str:
                return "Hello, world!"

            @server.resource("resource://my-resource")
            async def get_data() -> str:
                data = await fetch_data()
                return f"Hello, world! {data}"

            @server.resource("resource://{city}/weather")
            def get_weather(city: str) -> str:
                return f"Weather for {city}"

            @server.resource("resource://{city}/weather")
            async def get_weather(city: str) -> str:
                data = await fetch_weather(city)
                return f"Weather for {city}: {data}"
            ```
        """
        # Check if user passed function directly instead of calling decorator
        if callable(uri):
            raise TypeError(
                "The @resource decorator was used incorrectly. "
                "Did you forget to call it? Use @resource('uri') instead of @resource"
            )

        def decorator(fn: _CallableT) -> _CallableT:
            # Check if this should be a template
            sig = inspect.signature(fn)
            has_uri_params = "{" in uri and "}" in uri
            has_func_params = bool(sig.parameters)

            if has_uri_params or has_func_params:
                # Check for Context parameter to exclude from validation
                context_param = find_context_parameter(fn)

                # Validate that URI params match function params (excluding context)
                uri_params = set(re.findall(r"{(\w+)}", uri))
                # We need to remove the context_param from the resource function if
                # there is any.
                func_params = {p for p in sig.parameters.keys() if p != context_param}

                if uri_params != func_params:
                    raise ValueError(
                        f"Mismatch between URI parameters {uri_params} and function parameters {func_params}"
                    )

                # Register as template
                self._resource_manager.add_template(
                    fn=fn,
                    uri_template=uri,
                    name=name,
                    title=title,
                    description=description,
                    mime_type=mime_type,
                    icons=icons,
                    annotations=annotations,
                    meta=meta,
                )
            else:
                # Register as regular resource
                resource = FunctionResource.from_function(
                    fn=fn,
                    uri=uri,
                    name=name,
                    title=title,
                    description=description,
                    mime_type=mime_type,
                    icons=icons,
                    annotations=annotations,
                    meta=meta,
                )
                self.add_resource(resource)
            return fn

        return decorator

    def add_prompt(self, prompt: Prompt) -> None:
        """Add a prompt to the server.

        Args:
            prompt: A Prompt instance to add
        """
        self._prompt_manager.add_prompt(prompt)

    def prompt(
        self,
        name: str | None = None,
        title: str | None = None,
        description: str | None = None,
        icons: list[Icon] | None = None,
    ) -> Callable[[_CallableT], _CallableT]:
        """Decorator to register a prompt.

        Args:
            name: Optional name for the prompt (defaults to function name)
            title: Optional human-readable title for the prompt
            description: Optional description of what the prompt does
            icons: Optional list of icons for the prompt

        Example:
            ```python
            @server.prompt()
            def analyze_table(table_name: str) -> list[Message]:
                schema = read_table_schema(table_name)
                return [
                    {
                        "role": "user",
                        "content": f"Analyze this schema:\n{schema}"
                    }
                ]

            @server.prompt()
            async def analyze_file(path: str) -> list[Message]:
                content = await read_file(path)
                return [
                    {
                        "role": "user",
                        "content": {
                            "type": "resource",
                            "resource": {
                                "uri": f"file://{path}",
                                "text": content
                            }
                        }
                    }
                ]
            ```
        """
        # Check if user passed function directly instead of calling decorator
        if callable(name):
            raise TypeError(
                "The @prompt decorator was used incorrectly. "
                "Did you forget to call it? Use @prompt() instead of @prompt"
            )

        def decorator(func: _CallableT) -> _CallableT:
            prompt = Prompt.from_function(func, name=name, title=title, description=description, icons=icons)
            self.add_prompt(prompt)
            return func

        return decorator

    def custom_route(
        self,
        path: str,
        methods: list[str],
        name: str | None = None,
        include_in_schema: bool = True,
    ):
        """Decorator to register a custom HTTP route on the MCP server.

        Allows adding arbitrary HTTP endpoints outside the standard MCP protocol,
        which can be useful for OAuth callbacks, health checks, or admin APIs.
        The handler function must be an async function that accepts a Starlette
        Request and returns a Response.

        Routes using this decorator will not require authorization. It is intended
        for uses that are either a part of authorization flows or intended to be
        public such as health check endpoints.

        Args:
            path: URL path for the route (e.g., "/oauth/callback")
            methods: List of HTTP methods to support (e.g., ["GET", "POST"])
            name: Optional name for the route (to reference this route with
                  Starlette's reverse URL lookup feature)
            include_in_schema: Whether to include in OpenAPI schema, defaults to True

        Example:
            ```python
            @server.custom_route("/health", methods=["GET"])
            async def health_check(request: Request) -> Response:
                return JSONResponse({"status": "ok"})
            ```
        """

        def decorator(  # pragma: no cover
            func: Callable[[Request], Awaitable[Response]],
        ) -> Callable[[Request], Awaitable[Response]]:
            self._custom_starlette_routes.append(
                Route(path, endpoint=func, methods=methods, name=name, include_in_schema=include_in_schema)
            )
            return func

        return decorator  # pragma: no cover

    async def run_stdio_async(self) -> None:
        """Run the server using stdio transport."""
        async with stdio_server() as (read_stream, write_stream):
            await self._lowlevel_server.run(
                read_stream,
                write_stream,
                self._lowlevel_server.create_initialization_options(),
            )

    async def run_sse_async(  # pragma: no cover
        self,
        *,
        host: str = "127.0.0.1",
        port: int = 8000,
        sse_path: str = "/sse",
        message_path: str = "/messages/",
        transport_security: TransportSecuritySettings | None = None,
    ) -> None:
        """Run the server using SSE transport."""
        import uvicorn

        starlette_app = self.sse_app(
            sse_path=sse_path,
            message_path=message_path,
            transport_security=transport_security,
            host=host,
        )

        config = uvicorn.Config(
            starlette_app,
            host=host,
            port=port,
            log_level=self.settings.log_level.lower(),
        )
        server = uvicorn.Server(config)
        await server.serve()

    async def run_streamable_http_async(  # pragma: no cover
        self,
        *,
        host: str = "127.0.0.1",
        port: int = 8000,
        streamable_http_path: str = "/mcp",
        json_response: bool = False,
        stateless_http: bool = False,
        event_store: EventStore | None = None,
        retry_interval: int | None = None,
        transport_security: TransportSecuritySettings | None = None,
    ) -> None:
        """Run the server using StreamableHTTP transport."""
        import uvicorn

        starlette_app = self.streamable_http_app(
            streamable_http_path=streamable_http_path,
            json_response=json_response,
            stateless_http=stateless_http,
            event_store=event_store,
            retry_interval=retry_interval,
            transport_security=transport_security,
            host=host,
        )

        config = uvicorn.Config(
            starlette_app,
            host=host,
            port=port,
            log_level=self.settings.log_level.lower(),
        )
        server = uvicorn.Server(config)
        await server.serve()

    def sse_app(
        self,
        *,
        sse_path: str = "/sse",
        message_path: str = "/messages/",
        transport_security: TransportSecuritySettings | None = None,
        host: str = "127.0.0.1",
    ) -> Starlette:
        """Return an instance of the SSE server app."""
        # Auto-enable DNS rebinding protection for localhost (IPv4 and IPv6)
        if transport_security is None and host in ("127.0.0.1", "localhost", "::1"):
            transport_security = TransportSecuritySettings(
                enable_dns_rebinding_protection=True,
                allowed_hosts=["127.0.0.1:*", "localhost:*", "[::1]:*"],
                allowed_origins=["http://127.0.0.1:*", "http://localhost:*", "http://[::1]:*"],
            )

        sse = SseServerTransport(message_path, security_settings=transport_security)

        async def handle_sse(scope: Scope, receive: Receive, send: Send):  # pragma: no cover
            # Add client ID from auth context into request context if available

            async with sse.connect_sse(scope, receive, send) as streams:
                await self._lowlevel_server.run(
                    streams[0], streams[1], self._lowlevel_server.create_initialization_options()
                )
            return Response()

        # Create routes
        routes: list[Route | Mount] = []
        middleware: list[Middleware] = []
        required_scopes: list[str] = []

        # Set up auth if configured
        if self.settings.auth:  # pragma: no cover
            required_scopes = self.settings.auth.required_scopes or []

            # Add auth middleware if token verifier is available
            if self._token_verifier:
                middleware = [
                    # extract auth info from request (but do not require it)
                    Middleware(
                        AuthenticationMiddleware,
                        backend=BearerAuthBackend(self._token_verifier),
                    ),
                    # Add the auth context middleware to store
                    # authenticated user in a contextvar
                    Middleware(AuthContextMiddleware),
                ]

            # Add auth endpoints if auth server provider is configured
            if self._auth_server_provider:
                from mcp.server.auth.routes import create_auth_routes

                routes.extend(
                    create_auth_routes(
                        provider=self._auth_server_provider,
                        issuer_url=self.settings.auth.issuer_url,
                        service_documentation_url=self.settings.auth.service_documentation_url,
                        client_registration_options=self.settings.auth.client_registration_options,
                        revocation_options=self.settings.auth.revocation_options,
                    )
                )

        # When auth is configured, require authentication
        if self._token_verifier:  # pragma: no cover
            # Determine resource metadata URL
            resource_metadata_url = None
            if self.settings.auth and self.settings.auth.resource_server_url:
                from mcp.server.auth.routes import build_resource_metadata_url

                # Build compliant metadata URL for WWW-Authenticate header
                resource_metadata_url = build_resource_metadata_url(self.settings.auth.resource_server_url)

            # Auth is enabled, wrap the endpoints with RequireAuthMiddleware
            routes.append(
                Route(
                    sse_path,
                    endpoint=RequireAuthMiddleware(handle_sse, required_scopes, resource_metadata_url),
                    methods=["GET"],
                )
            )
            routes.append(
                Mount(
                    message_path,
                    app=RequireAuthMiddleware(sse.handle_post_message, required_scopes, resource_metadata_url),
                )
            )
        else:
            # Auth is disabled, no need for RequireAuthMiddleware
            # Since handle_sse is an ASGI app, we need to create a compatible endpoint
            async def sse_endpoint(request: Request) -> Response:  # pragma: no cover
                # Convert the Starlette request to ASGI parameters
                return await handle_sse(request.scope, request.receive, request._send)  # type: ignore[reportPrivateUsage]

            routes.append(
                Route(
                    sse_path,
                    endpoint=sse_endpoint,
                    methods=["GET"],
                )
            )
            routes.append(
                Mount(
                    message_path,
                    app=sse.handle_post_message,
                )
            )
        # Add protected resource metadata endpoint if configured as RS
        if self.settings.auth and self.settings.auth.resource_server_url:  # pragma: no cover
            from mcp.server.auth.routes import create_protected_resource_routes

            routes.extend(
                create_protected_resource_routes(
                    resource_url=self.settings.auth.resource_server_url,
                    authorization_servers=[self.settings.auth.issuer_url],
                    scopes_supported=self.settings.auth.required_scopes,
                )
            )

        # mount these routes last, so they have the lowest route matching precedence
        routes.extend(self._custom_starlette_routes)

        # Create Starlette app with routes and middleware
        return Starlette(debug=self.settings.debug, routes=routes, middleware=middleware)

    def streamable_http_app(
        self,
        *,
        streamable_http_path: str = "/mcp",
        json_response: bool = False,
        stateless_http: bool = False,
        event_store: EventStore | None = None,
        retry_interval: int | None = None,
        transport_security: TransportSecuritySettings | None = None,
        host: str = "127.0.0.1",
    ) -> Starlette:
        """Return an instance of the StreamableHTTP server app."""
        return self._lowlevel_server.streamable_http_app(
            streamable_http_path=streamable_http_path,
            json_response=json_response,
            stateless_http=stateless_http,
            event_store=event_store,
            retry_interval=retry_interval,
            transport_security=transport_security,
            host=host,
            auth=self.settings.auth,
            token_verifier=self._token_verifier,
            auth_server_provider=self._auth_server_provider,
            custom_starlette_routes=self._custom_starlette_routes,
            debug=self.settings.debug,
        )

    async def list_prompts(self) -> list[MCPPrompt]:
        """List all available prompts."""
        prompts = self._prompt_manager.list_prompts()
        return [
            MCPPrompt(
                name=prompt.name,
                title=prompt.title,
                description=prompt.description,
                arguments=[
                    MCPPromptArgument(
                        name=arg.name,
                        description=arg.description,
                        required=arg.required,
                    )
                    for arg in (prompt.arguments or [])
                ],
                icons=prompt.icons,
            )
            for prompt in prompts
        ]

    async def get_prompt(
        self, name: str, arguments: dict[str, Any] | None = None, context: Context[LifespanResultT, Any] | None = None
    ) -> GetPromptResult:
        """Get a prompt by name with arguments."""
        if context is None:
            context = Context(mcp_server=self)
        try:
            prompt = self._prompt_manager.get_prompt(name)
            if not prompt:
                raise PromptError(f"Unknown prompt: {name}")

            messages = await prompt.render(arguments, context)

            return GetPromptResult(
                description=prompt.description,
                messages=pydantic_core.to_jsonable_python(messages),
            )
        except (PromptError, MCPError):
            raise
        except Exception as e:
            logger.exception(f"Error getting prompt {name}")
            raise PromptError(f"Error getting prompt {name}") from e