Rename FastMCP to MCPServer (#1951)

src/mcp/server/__init__.py

@@ -1,5 +1,5 @@
-from .fastmcp import FastMCP
 from .lowlevel import NotificationOptions, Server
+from .mcpserver import MCPServer
 from .models import InitializationOptions
 
-__all__ = ["Server", "FastMCP", "NotificationOptions", "InitializationOptions"]
+__all__ = ["Server", "MCPServer", "NotificationOptions", "InitializationOptions"]

src/mcp/server/auth/provider.py

@@ -96,7 +96,7 @@ class TokenVerifier(Protocol):
         """Verify a bearer token and return access info if valid."""
 
 
-# NOTE: FastMCP doesn't render any of these types in the user response, so it's
+# NOTE: MCPServer doesn't render any of these types in the user response, so it's
 # OK to add fields to subclasses which should not be exposed externally.
 AuthorizationCodeT = TypeVar("AuthorizationCodeT", bound=AuthorizationCode)
 RefreshTokenT = TypeVar("RefreshTokenT", bound=RefreshToken)

src/mcp/server/fastmcp/__init__.py

@@ -1,8 +0,0 @@
-"""FastMCP - A more ergonomic interface for MCP servers."""
-
-from mcp.types import Icon
-
-from .server import Context, FastMCP
-from .utilities.types import Audio, Image
-
-__all__ = ["FastMCP", "Context", "Image", "Audio", "Icon"]

src/mcp/server/fastmcp/exceptions.py

@@ -1,21 +0,0 @@
-"""Custom exceptions for FastMCP."""
-
-
-class FastMCPError(Exception):
-    """Base error for FastMCP."""
-
-
-class ValidationError(FastMCPError):
-    """Error in validating parameters or return values."""
-
-
-class ResourceError(FastMCPError):
-    """Error in resource operations."""
-
-
-class ToolError(FastMCPError):
-    """Error in tool operations."""
-
-
-class InvalidSignature(Exception):
-    """Invalid signature for use with FastMCP."""

src/mcp/server/fastmcp/utilities/__init__.py

@@ -1 +0,0 @@
-"""FastMCP utility modules."""

src/mcp/server/mcpserver/__init__.py

@@ -0,0 +1,8 @@
+"""MCPServer - A more ergonomic interface for MCP servers."""
+
+from mcp.types import Icon
+
+from .server import Context, MCPServer
+from .utilities.types import Audio, Image
+
+__all__ = ["MCPServer", "Context", "Image", "Audio", "Icon"]

src/mcp/server/mcpserver/exceptions.py

@@ -0,0 +1,21 @@
+"""Custom exceptions for MCPServer."""
+
+
+class MCPServerError(Exception):
+    """Base error for MCPServer."""
+
+
+class ValidationError(MCPServerError):
+    """Error in validating parameters or return values."""
+
+
+class ResourceError(MCPServerError):
+    """Error in resource operations."""
+
+
+class ToolError(MCPServerError):
+    """Error in tool operations."""
+
+
+class InvalidSignature(Exception):
+    """Invalid signature for use with MCPServer."""

src/mcp/server/mcpserver/prompts/__init__.py

@@ -0,0 +1,4 @@
+from .base import Prompt
+from .manager import PromptManager
+
+__all__ = ["Prompt", "PromptManager"]

src/mcp/server/mcpserver/prompts/base.py

@@ -0,0 +1,183 @@
+"""Base classes for MCPServer prompts."""
+
+from __future__ import annotations
+
+import inspect
+from collections.abc import Awaitable, Callable, Sequence
+from typing import TYPE_CHECKING, Any, Literal
+
+import pydantic_core
+from pydantic import BaseModel, Field, TypeAdapter, validate_call
+
+from mcp.server.mcpserver.utilities.context_injection import find_context_parameter, inject_context
+from mcp.server.mcpserver.utilities.func_metadata import func_metadata
+from mcp.types import ContentBlock, Icon, TextContent
+
+if TYPE_CHECKING:
+    from mcp.server.mcpserver.server import Context
+    from mcp.server.session import ServerSessionT
+    from mcp.shared.context import LifespanContextT, RequestT
+
+
+class Message(BaseModel):
+    """Base class for all prompt messages."""
+
+    role: Literal["user", "assistant"]
+    content: ContentBlock
+
+    def __init__(self, content: str | ContentBlock, **kwargs: Any):
+        if isinstance(content, str):
+            content = TextContent(type="text", text=content)
+        super().__init__(content=content, **kwargs)
+
+
+class UserMessage(Message):
+    """A message from the user."""
+
+    role: Literal["user", "assistant"] = "user"
+
+    def __init__(self, content: str | ContentBlock, **kwargs: Any):
+        super().__init__(content=content, **kwargs)
+
+
+class AssistantMessage(Message):
+    """A message from the assistant."""
+
+    role: Literal["user", "assistant"] = "assistant"
+
+    def __init__(self, content: str | ContentBlock, **kwargs: Any):
+        super().__init__(content=content, **kwargs)
+
+
+message_validator = TypeAdapter[UserMessage | AssistantMessage](UserMessage | AssistantMessage)
+
+SyncPromptResult = str | Message | dict[str, Any] | Sequence[str | Message | dict[str, Any]]
+PromptResult = SyncPromptResult | Awaitable[SyncPromptResult]
+
+
+class PromptArgument(BaseModel):
+    """An argument that can be passed to a prompt."""
+
+    name: str = Field(description="Name of the argument")
+    description: str | None = Field(None, description="Description of what the argument does")
+    required: bool = Field(default=False, description="Whether the argument is required")
+
+
+class Prompt(BaseModel):
+    """A prompt template that can be rendered with parameters."""
+
+    name: str = Field(description="Name of the prompt")
+    title: str | None = Field(None, description="Human-readable title of the prompt")
+    description: str | None = Field(None, description="Description of what the prompt does")
+    arguments: list[PromptArgument] | None = Field(None, description="Arguments that can be passed to the prompt")
+    fn: Callable[..., PromptResult | Awaitable[PromptResult]] = Field(exclude=True)
+    icons: list[Icon] | None = Field(default=None, description="Optional list of icons for this prompt")
+    context_kwarg: str | None = Field(None, description="Name of the kwarg that should receive context", exclude=True)
+
+    @classmethod
+    def from_function(
+        cls,
+        fn: Callable[..., PromptResult | Awaitable[PromptResult]],
+        name: str | None = None,
+        title: str | None = None,
+        description: str | None = None,
+        icons: list[Icon] | None = None,
+        context_kwarg: str | None = None,
+    ) -> Prompt:
+        """Create a Prompt from a function.
+
+        The function can return:
+        - A string (converted to a message)
+        - A Message object
+        - A dict (converted to a message)
+        - A sequence of any of the above
+        """
+        func_name = name or fn.__name__
+
+        if func_name == "<lambda>":  # pragma: no cover
+            raise ValueError("You must provide a name for lambda functions")
+
+        # Find context parameter if it exists
+        if context_kwarg is None:  # pragma: no branch
+            context_kwarg = find_context_parameter(fn)
+
+        # Get schema from func_metadata, excluding context parameter
+        func_arg_metadata = func_metadata(
+            fn,
+            skip_names=[context_kwarg] if context_kwarg is not None else [],
+        )
+        parameters = func_arg_metadata.arg_model.model_json_schema()
+
+        # Convert parameters to PromptArguments
+        arguments: list[PromptArgument] = []
+        if "properties" in parameters:  # pragma: no branch
+            for param_name, param in parameters["properties"].items():
+                required = param_name in parameters.get("required", [])
+                arguments.append(
+                    PromptArgument(
+                        name=param_name,
+                        description=param.get("description"),
+                        required=required,
+                    )
+                )
+
+        # ensure the arguments are properly cast
+        fn = validate_call(fn)
+
+        return cls(
+            name=func_name,
+            title=title,
+            description=description or fn.__doc__ or "",
+            arguments=arguments,
+            fn=fn,
+            icons=icons,
+            context_kwarg=context_kwarg,
+        )
+
+    async def render(
+        self,
+        arguments: dict[str, Any] | None = None,
+        context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,
+    ) -> list[Message]:
+        """Render the prompt with arguments."""
+        # Validate required arguments
+        if self.arguments:
+            required = {arg.name for arg in self.arguments if arg.required}
+            provided = set(arguments or {})
+            missing = required - provided
+            if missing:
+                raise ValueError(f"Missing required arguments: {missing}")
+
+        try:
+            # Add context to arguments if needed
+            call_args = inject_context(self.fn, arguments or {}, context, self.context_kwarg)
+
+            # Call function and check if result is a coroutine
+            result = self.fn(**call_args)
+            if inspect.iscoroutine(result):
+                result = await result
+
+            # Validate messages
+            if not isinstance(result, list | tuple):
+                result = [result]
+
+            # Convert result to messages
+            messages: list[Message] = []
+            for msg in result:  # type: ignore[reportUnknownVariableType]
+                try:
+                    if isinstance(msg, Message):
+                        messages.append(msg)
+                    elif isinstance(msg, dict):
+                        messages.append(message_validator.validate_python(msg))
+                    elif isinstance(msg, str):
+                        content = TextContent(type="text", text=msg)
+                        messages.append(UserMessage(content=content))
+                    else:  # pragma: no cover
+                        content = pydantic_core.to_json(msg, fallback=str, indent=2).decode()
+                        messages.append(Message(role="user", content=content))
+                except Exception:  # pragma: no cover
+                    raise ValueError(f"Could not convert prompt result to message: {msg}")
+
+            return messages
+        except Exception as e:  # pragma: no cover
+            raise ValueError(f"Error rendering prompt {self.name}: {e}")

src/mcp/server/mcpserver/prompts/manager.py

@@ -0,0 +1,60 @@
+"""Prompt management functionality."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+
+from mcp.server.mcpserver.prompts.base import Message, Prompt
+from mcp.server.mcpserver.utilities.logging import get_logger
+
+if TYPE_CHECKING:
+    from mcp.server.mcpserver.server import Context
+    from mcp.server.session import ServerSessionT
+    from mcp.shared.context import LifespanContextT, RequestT
+
+logger = get_logger(__name__)
+
+
+class PromptManager:
+    """Manages MCPServer prompts."""
+
+    def __init__(self, warn_on_duplicate_prompts: bool = True):
+        self._prompts: dict[str, Prompt] = {}
+        self.warn_on_duplicate_prompts = warn_on_duplicate_prompts
+
+    def get_prompt(self, name: str) -> Prompt | None:
+        """Get prompt by name."""
+        return self._prompts.get(name)
+
+    def list_prompts(self) -> list[Prompt]:
+        """List all registered prompts."""
+        return list(self._prompts.values())
+
+    def add_prompt(
+        self,
+        prompt: Prompt,
+    ) -> Prompt:
+        """Add a prompt to the manager."""
+
+        # Check for duplicates
+        existing = self._prompts.get(prompt.name)
+        if existing:
+            if self.warn_on_duplicate_prompts:
+                logger.warning(f"Prompt already exists: {prompt.name}")
+            return existing
+
+        self._prompts[prompt.name] = prompt
+        return prompt
+
+    async def render_prompt(
+        self,
+        name: str,
+        arguments: dict[str, Any] | None = None,
+        context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,
+    ) -> list[Message]:
+        """Render a prompt by name with arguments."""
+        prompt = self.get_prompt(name)
+        if not prompt:
+            raise ValueError(f"Unknown prompt: {name}")
+
+        return await prompt.render(arguments, context=context)

src/mcp/server/mcpserver/resources/__init__.py

@@ -0,0 +1,23 @@
+from .base import Resource
+from .resource_manager import ResourceManager
+from .templates import ResourceTemplate
+from .types import (
+    BinaryResource,
+    DirectoryResource,
+    FileResource,
+    FunctionResource,
+    HttpResource,
+    TextResource,
+)
+
+__all__ = [
+    "Resource",
+    "TextResource",
+    "BinaryResource",
+    "FunctionResource",
+    "FileResource",
+    "HttpResource",
+    "DirectoryResource",
+    "ResourceTemplate",
+    "ResourceManager",
+]

src/mcp/server/mcpserver/resources/base.py

@@ -0,0 +1,48 @@
+"""Base classes and interfaces for MCPServer resources."""
+
+import abc
+from typing import Any
+
+from pydantic import (
+    BaseModel,
+    ConfigDict,
+    Field,
+    ValidationInfo,
+    field_validator,
+)
+
+from mcp.types import Annotations, Icon
+
+
+class Resource(BaseModel, abc.ABC):
+    """Base class for all resources."""
+
+    model_config = ConfigDict(validate_default=True)
+
+    uri: str = Field(default=..., description="URI of the resource")
+    name: str | None = Field(description="Name of the resource", default=None)
+    title: str | None = Field(description="Human-readable title of the resource", default=None)
+    description: str | None = Field(description="Description of the resource", default=None)
+    mime_type: str = Field(
+        default="text/plain",
+        description="MIME type of the resource content",
+        pattern=r"^[a-zA-Z0-9]+/[a-zA-Z0-9\-+.]+(;\s*[a-zA-Z0-9\-_.]+=[a-zA-Z0-9\-_.]+)*$",
+    )
+    icons: list[Icon] | None = Field(default=None, description="Optional list of icons for this resource")
+    annotations: Annotations | None = Field(default=None, description="Optional annotations for the resource")
+    meta: dict[str, Any] | None = Field(default=None, description="Optional metadata for this resource")
+
+    @field_validator("name", mode="before")
+    @classmethod
+    def set_default_name(cls, name: str | None, info: ValidationInfo) -> str:
+        """Set default name from URI if not provided."""
+        if name:
+            return name
+        if uri := info.data.get("uri"):
+            return str(uri)
+        raise ValueError("Either name or uri must be provided")
+
+    @abc.abstractmethod
+    async def read(self) -> str | bytes:
+        """Read the resource content."""
+        pass  # pragma: no cover

src/mcp/server/mcpserver/resources/resource_manager.py

@@ -0,0 +1,115 @@
+"""Resource manager functionality."""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from typing import TYPE_CHECKING, Any
+
+from pydantic import AnyUrl
+
+from mcp.server.mcpserver.resources.base import Resource
+from mcp.server.mcpserver.resources.templates import ResourceTemplate
+from mcp.server.mcpserver.utilities.logging import get_logger
+from mcp.types import Annotations, Icon
+
+if TYPE_CHECKING:
+    from mcp.server.mcpserver.server import Context
+    from mcp.server.session import ServerSessionT
+    from mcp.shared.context import LifespanContextT, RequestT
+
+logger = get_logger(__name__)
+
+
+class ResourceManager:
+    """Manages MCPServer resources."""
+
+    def __init__(self, warn_on_duplicate_resources: bool = True):
+        self._resources: dict[str, Resource] = {}
+        self._templates: dict[str, ResourceTemplate] = {}
+        self.warn_on_duplicate_resources = warn_on_duplicate_resources
+
+    def add_resource(self, resource: Resource) -> Resource:
+        """Add a resource to the manager.
+
+        Args:
+            resource: A Resource instance to add
+
+        Returns:
+            The added resource. If a resource with the same URI already exists,
+            returns the existing resource.
+        """
+        logger.debug(
+            "Adding resource",
+            extra={
+                "uri": resource.uri,
+                "type": type(resource).__name__,
+                "resource_name": resource.name,
+            },
+        )
+        existing = self._resources.get(str(resource.uri))
+        if existing:
+            if self.warn_on_duplicate_resources:
+                logger.warning(f"Resource already exists: {resource.uri}")
+            return existing
+        self._resources[str(resource.uri)] = resource
+        return resource
+
+    def add_template(
+        self,
+        fn: Callable[..., Any],
+        uri_template: 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,
+    ) -> ResourceTemplate:
+        """Add a template from a function."""
+        template = ResourceTemplate.from_function(
+            fn,
+            uri_template=uri_template,
+            name=name,
+            title=title,
+            description=description,
+            mime_type=mime_type,
+            icons=icons,
+            annotations=annotations,
+            meta=meta,
+        )
+        self._templates[template.uri_template] = template
+        return template
+
+    async def get_resource(
+        self,
+        uri: AnyUrl | str,
+        context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,
+    ) -> Resource | None:
+        """Get resource by URI, checking concrete resources first, then templates."""
+        uri_str = str(uri)
+        logger.debug("Getting resource", extra={"uri": uri_str})
+
+        # First check concrete resources
+        if resource := self._resources.get(uri_str):
+            return resource
+
+        # Then check templates
+        for template in self._templates.values():
+            if params := template.matches(uri_str):
+                try:
+                    return await template.create_resource(uri_str, params, context=context)
+                except Exception as e:  # pragma: no cover
+                    raise ValueError(f"Error creating resource from template: {e}")
+
+        raise ValueError(f"Unknown resource: {uri}")
+
+    def list_resources(self) -> list[Resource]:
+        """List all registered resources."""
+        logger.debug("Listing resources", extra={"count": len(self._resources)})
+        return list(self._resources.values())
+
+    def list_templates(self) -> list[ResourceTemplate]:
+        """List all registered templates."""
+        logger.debug("Listing templates", extra={"count": len(self._templates)})
+        return list(self._templates.values())

src/mcp/server/mcpserver/resources/templates.py

@@ -0,0 +1,127 @@
+"""Resource template functionality."""
+
+from __future__ import annotations
+
+import inspect
+import re
+from collections.abc import Callable
+from typing import TYPE_CHECKING, Any
+from urllib.parse import unquote
+
+from pydantic import BaseModel, Field, validate_call
+
+from mcp.server.mcpserver.resources.types import FunctionResource, Resource
+from mcp.server.mcpserver.utilities.context_injection import find_context_parameter, inject_context
+from mcp.server.mcpserver.utilities.func_metadata import func_metadata
+from mcp.types import Annotations, Icon
+
+if TYPE_CHECKING:
+    from mcp.server.mcpserver.server import Context
+    from mcp.server.session import ServerSessionT
+    from mcp.shared.context import LifespanContextT, RequestT
+
+
+class ResourceTemplate(BaseModel):
+    """A template for dynamically creating resources."""
+
+    uri_template: str = Field(description="URI template with parameters (e.g. weather://{city}/current)")
+    name: str = Field(description="Name of the resource")
+    title: str | None = Field(description="Human-readable title of the resource", default=None)
+    description: str | None = Field(description="Description of what the resource does")
+    mime_type: str = Field(default="text/plain", description="MIME type of the resource content")
+    icons: list[Icon] | None = Field(default=None, description="Optional list of icons for the resource template")
+    annotations: Annotations | None = Field(default=None, description="Optional annotations for the resource template")
+    meta: dict[str, Any] | None = Field(default=None, description="Optional metadata for this resource template")
+    fn: Callable[..., Any] = Field(exclude=True)
+    parameters: dict[str, Any] = Field(description="JSON schema for function parameters")
+    context_kwarg: str | None = Field(None, description="Name of the kwarg that should receive context")
+
+    @classmethod
+    def from_function(
+        cls,
+        fn: Callable[..., Any],
+        uri_template: 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,
+        context_kwarg: str | None = None,
+    ) -> ResourceTemplate:
+        """Create a template from a function."""
+        func_name = name or fn.__name__
+        if func_name == "<lambda>":
+            raise ValueError("You must provide a name for lambda functions")  # pragma: no cover
+
+        # Find context parameter if it exists
+        if context_kwarg is None:  # pragma: no branch
+            context_kwarg = find_context_parameter(fn)
+
+        # Get schema from func_metadata, excluding context parameter
+        func_arg_metadata = func_metadata(
+            fn,
+            skip_names=[context_kwarg] if context_kwarg is not None else [],
+        )
+        parameters = func_arg_metadata.arg_model.model_json_schema()
+
+        # ensure the arguments are properly cast
+        fn = validate_call(fn)
+
+        return cls(
+            uri_template=uri_template,
+            name=func_name,
+            title=title,
+            description=description or fn.__doc__ or "",
+            mime_type=mime_type or "text/plain",
+            icons=icons,
+            annotations=annotations,
+            meta=meta,
+            fn=fn,
+            parameters=parameters,
+            context_kwarg=context_kwarg,
+        )
+
+    def matches(self, uri: str) -> dict[str, Any] | None:
+        """Check if URI matches template and extract parameters.
+
+        Extracted parameters are URL-decoded to handle percent-encoded characters.
+        """
+        # Convert template to regex pattern
+        pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")
+        match = re.match(f"^{pattern}$", uri)
+        if match:
+            # URL-decode all extracted parameter values
+            return {key: unquote(value) for key, value in match.groupdict().items()}
+        return None
+
+    async def create_resource(
+        self,
+        uri: str,
+        params: dict[str, Any],
+        context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,
+    ) -> Resource:
+        """Create a resource from the template with the given parameters."""
+        try:
+            # Add context to params if needed
+            params = inject_context(self.fn, params, context, self.context_kwarg)
+
+            # Call function and check if result is a coroutine
+            result = self.fn(**params)
+            if inspect.iscoroutine(result):
+                result = await result
+
+            return FunctionResource(
+                uri=uri,  # type: ignore
+                name=self.name,
+                title=self.title,
+                description=self.description,
+                mime_type=self.mime_type,
+                icons=self.icons,
+                annotations=self.annotations,
+                meta=self.meta,
+                fn=lambda: result,  # Capture result in closure
+            )
+        except Exception as e:
+            raise ValueError(f"Error creating resource from template: {e}")

src/mcp/server/mcpserver/resources/types.py

@@ -0,0 +1,203 @@
+"""Concrete resource implementations."""
+
+import inspect
+import json
+from collections.abc import Callable
+from pathlib import Path
+from typing import Any
+
+import anyio
+import anyio.to_thread
+import httpx
+import pydantic
+import pydantic_core
+from pydantic import Field, ValidationInfo, validate_call
+
+from mcp.server.mcpserver.resources.base import Resource
+from mcp.types import Annotations, Icon
+
+
+class TextResource(Resource):
+    """A resource that reads from a string."""
+
+    text: str = Field(description="Text content of the resource")
+
+    async def read(self) -> str:
+        """Read the text content."""
+        return self.text  # pragma: no cover
+
+
+class BinaryResource(Resource):
+    """A resource that reads from bytes."""
+
+    data: bytes = Field(description="Binary content of the resource")
+
+    async def read(self) -> bytes:
+        """Read the binary content."""
+        return self.data  # pragma: no cover
+
+
+class FunctionResource(Resource):
+    """A resource that defers data loading by wrapping a function.
+
+    The function is only called when the resource is read, allowing for lazy loading
+    of potentially expensive data. This is particularly useful when listing resources,
+    as the function won't be called until the resource is actually accessed.
+
+    The function can return:
+    - str for text content (default)
+    - bytes for binary content
+    - other types will be converted to JSON
+    """
+
+    fn: Callable[[], Any] = Field(exclude=True)
+
+    async def read(self) -> str | bytes:
+        """Read the resource by calling the wrapped function."""
+        try:
+            # Call the function first to see if it returns a coroutine
+            result = self.fn()
+            # If it's a coroutine, await it
+            if inspect.iscoroutine(result):
+                result = await result
+
+            if isinstance(result, Resource):  # pragma: no cover
+                return await result.read()
+            elif isinstance(result, bytes):
+                return result
+            elif isinstance(result, str):
+                return result
+            else:
+                return pydantic_core.to_json(result, fallback=str, indent=2).decode()
+        except Exception as e:
+            raise ValueError(f"Error reading resource {self.uri}: {e}")
+
+    @classmethod
+    def from_function(
+        cls,
+        fn: Callable[..., Any],
+        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,
+    ) -> "FunctionResource":
+        """Create a FunctionResource from a function."""
+        func_name = name or fn.__name__
+        if func_name == "<lambda>":  # pragma: no cover
+            raise ValueError("You must provide a name for lambda functions")
+
+        # ensure the arguments are properly cast
+        fn = validate_call(fn)
+
+        return cls(
+            uri=uri,
+            name=func_name,
+            title=title,
+            description=description or fn.__doc__ or "",
+            mime_type=mime_type or "text/plain",
+            fn=fn,
+            icons=icons,
+            annotations=annotations,
+            meta=meta,
+        )
+
+
+class FileResource(Resource):
+    """A resource that reads from a file.
+
+    Set is_binary=True to read file as binary data instead of text.
+    """
+
+    path: Path = Field(description="Path to the file")
+    is_binary: bool = Field(
+        default=False,
+        description="Whether to read the file as binary data",
+    )
+    mime_type: str = Field(
+        default="text/plain",
+        description="MIME type of the resource content",
+    )
+
+    @pydantic.field_validator("path")
+    @classmethod
+    def validate_absolute_path(cls, path: Path) -> Path:
+        """Ensure path is absolute."""
+        if not path.is_absolute():
+            raise ValueError("Path must be absolute")
+        return path
+
+    @pydantic.field_validator("is_binary")
+    @classmethod
+    def set_binary_from_mime_type(cls, is_binary: bool, info: ValidationInfo) -> bool:
+        """Set is_binary based on mime_type if not explicitly set."""
+        if is_binary:
+            return True
+        mime_type = info.data.get("mime_type", "text/plain")
+        return not mime_type.startswith("text/")
+
+    async def read(self) -> str | bytes:
+        """Read the file content."""
+        try:
+            if self.is_binary:
+                return await anyio.to_thread.run_sync(self.path.read_bytes)
+            return await anyio.to_thread.run_sync(self.path.read_text)
+        except Exception as e:
+            raise ValueError(f"Error reading file {self.path}: {e}")
+
+
+class HttpResource(Resource):
+    """A resource that reads from an HTTP endpoint."""
+
+    url: str = Field(description="URL to fetch content from")
+    mime_type: str = Field(default="application/json", description="MIME type of the resource content")
+
+    async def read(self) -> str | bytes:
+        """Read the HTTP content."""
+        async with httpx.AsyncClient() as client:  # pragma: no cover
+            response = await client.get(self.url)
+            response.raise_for_status()
+            return response.text
+
+
+class DirectoryResource(Resource):
+    """A resource that lists files in a directory."""
+
+    path: Path = Field(description="Path to the directory")
+    recursive: bool = Field(default=False, description="Whether to list files recursively")
+    pattern: str | None = Field(default=None, description="Optional glob pattern to filter files")
+    mime_type: str = Field(default="application/json", description="MIME type of the resource content")
+
+    @pydantic.field_validator("path")
+    @classmethod
+    def validate_absolute_path(cls, path: Path) -> Path:  # pragma: no cover
+        """Ensure path is absolute."""
+        if not path.is_absolute():
+            raise ValueError("Path must be absolute")
+        return path
+
+    def list_files(self) -> list[Path]:  # pragma: no cover
+        """List files in the directory."""
+        if not self.path.exists():
+            raise FileNotFoundError(f"Directory not found: {self.path}")
+        if not self.path.is_dir():
+            raise NotADirectoryError(f"Not a directory: {self.path}")
+
+        try:
+            if self.pattern:
+                return list(self.path.glob(self.pattern)) if not self.recursive else list(self.path.rglob(self.pattern))
+            return list(self.path.glob("*")) if not self.recursive else list(self.path.rglob("*"))
+        except Exception as e:
+            raise ValueError(f"Error listing directory {self.path}: {e}")
+
+    async def read(self) -> str:  # Always returns JSON string  # pragma: no cover
+        """Read the directory listing."""
+        try:
+            files = await anyio.to_thread.run_sync(self.list_files)
+            file_list = [str(f.relative_to(self.path)) for f in files if f.is_file()]
+            return json.dumps({"files": file_list}, indent=2)
+        except Exception as e:
+            raise ValueError(f"Error reading directory {self.path}: {e}")

src/mcp/server/mcpserver/tools/__init__.py

@@ -0,0 +1,4 @@
+from .base import Tool
+from .tool_manager import ToolManager
+
+__all__ = ["Tool", "ToolManager"]

src/mcp/server/mcpserver/tools/base.py

@@ -0,0 +1,126 @@
+from __future__ import annotations
+
+import functools
+import inspect
+from collections.abc import Callable
+from functools import cached_property
+from typing import TYPE_CHECKING, Any
+
+from pydantic import BaseModel, Field
+
+from mcp.server.mcpserver.exceptions import ToolError
+from mcp.server.mcpserver.utilities.context_injection import find_context_parameter
+from mcp.server.mcpserver.utilities.func_metadata import FuncMetadata, func_metadata
+from mcp.shared.exceptions import UrlElicitationRequiredError
+from mcp.shared.tool_name_validation import validate_and_warn_tool_name
+from mcp.types import Icon, ToolAnnotations
+
+if TYPE_CHECKING:
+    from mcp.server.mcpserver.server import Context
+    from mcp.server.session import ServerSessionT
+    from mcp.shared.context import LifespanContextT, RequestT
+
+
+class Tool(BaseModel):
+    """Internal tool registration info."""
+
+    fn: Callable[..., Any] = Field(exclude=True)
+    name: str = Field(description="Name of the tool")
+    title: str | None = Field(None, description="Human-readable title of the tool")
+    description: str = Field(description="Description of what the tool does")
+    parameters: dict[str, Any] = Field(description="JSON schema for tool parameters")
+    fn_metadata: FuncMetadata = Field(
+        description="Metadata about the function including a pydantic model for tool arguments"
+    )
+    is_async: bool = Field(description="Whether the tool is async")
+    context_kwarg: str | None = Field(None, description="Name of the kwarg that should receive context")
+    annotations: ToolAnnotations | None = Field(None, description="Optional annotations for the tool")
+    icons: list[Icon] | None = Field(default=None, description="Optional list of icons for this tool")
+    meta: dict[str, Any] | None = Field(default=None, description="Optional metadata for this tool")
+
+    @cached_property
+    def output_schema(self) -> dict[str, Any] | None:
+        return self.fn_metadata.output_schema
+
+    @classmethod
+    def from_function(
+        cls,
+        fn: Callable[..., Any],
+        name: str | None = None,
+        title: str | None = None,
+        description: str | None = None,
+        context_kwarg: str | None = None,
+        annotations: ToolAnnotations | None = None,
+        icons: list[Icon] | None = None,
+        meta: dict[str, Any] | None = None,
+        structured_output: bool | None = None,
+    ) -> Tool:
+        """Create a Tool from a function."""
+        func_name = name or fn.__name__
+
+        validate_and_warn_tool_name(func_name)
+
+        if func_name == "<lambda>":
+            raise ValueError("You must provide a name for lambda functions")
+
+        func_doc = description or fn.__doc__ or ""
+        is_async = _is_async_callable(fn)
+
+        if context_kwarg is None:  # pragma: no branch
+            context_kwarg = find_context_parameter(fn)
+
+        func_arg_metadata = func_metadata(
+            fn,
+            skip_names=[context_kwarg] if context_kwarg is not None else [],
+            structured_output=structured_output,
+        )
+        parameters = func_arg_metadata.arg_model.model_json_schema(by_alias=True)
+
+        return cls(
+            fn=fn,
+            name=func_name,
+            title=title,
+            description=func_doc,
+            parameters=parameters,
+            fn_metadata=func_arg_metadata,
+            is_async=is_async,
+            context_kwarg=context_kwarg,
+            annotations=annotations,
+            icons=icons,
+            meta=meta,
+        )
+
+    async def run(
+        self,
+        arguments: dict[str, Any],
+        context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,
+        convert_result: bool = False,
+    ) -> Any:
+        """Run the tool with arguments."""
+        try:
+            result = await self.fn_metadata.call_fn_with_arg_validation(
+                self.fn,
+                self.is_async,
+                arguments,
+                {self.context_kwarg: context} if self.context_kwarg is not None else None,
+            )
+
+            if convert_result:
+                result = self.fn_metadata.convert_result(result)
+
+            return result
+        except UrlElicitationRequiredError:
+            # Re-raise UrlElicitationRequiredError so it can be properly handled
+            # as an MCP error response with code -32042
+            raise
+        except Exception as e:
+            raise ToolError(f"Error executing tool {self.name}: {e}") from e
+
+
+def _is_async_callable(obj: Any) -> bool:
+    while isinstance(obj, functools.partial):  # pragma: lax no cover
+        obj = obj.func
+
+    return inspect.iscoroutinefunction(obj) or (
+        callable(obj) and inspect.iscoroutinefunction(getattr(obj, "__call__", None))
+    )

src/mcp/server/mcpserver/tools/tool_manager.py

@@ -0,0 +1,93 @@
+from __future__ import annotations
+
+from collections.abc import Callable
+from typing import TYPE_CHECKING, Any
+
+from mcp.server.mcpserver.exceptions import ToolError
+from mcp.server.mcpserver.tools.base import Tool
+from mcp.server.mcpserver.utilities.logging import get_logger
+from mcp.shared.context import LifespanContextT, RequestT
+from mcp.types import Icon, ToolAnnotations
+
+if TYPE_CHECKING:
+    from mcp.server.mcpserver.server import Context
+    from mcp.server.session import ServerSessionT
+
+logger = get_logger(__name__)
+
+
+class ToolManager:
+    """Manages MCPServer tools."""
+
+    def __init__(
+        self,
+        warn_on_duplicate_tools: bool = True,
+        *,
+        tools: list[Tool] | None = None,
+    ):
+        self._tools: dict[str, Tool] = {}
+        if tools is not None:
+            for tool in tools:
+                if warn_on_duplicate_tools and tool.name in self._tools:
+                    logger.warning(f"Tool already exists: {tool.name}")
+                self._tools[tool.name] = tool
+
+        self.warn_on_duplicate_tools = warn_on_duplicate_tools
+
+    def get_tool(self, name: str) -> Tool | None:
+        """Get tool by name."""
+        return self._tools.get(name)
+
+    def list_tools(self) -> list[Tool]:
+        """List all registered tools."""
+        return list(self._tools.values())
+
+    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,
+    ) -> Tool:
+        """Add a tool to the server."""
+        tool = Tool.from_function(
+            fn,
+            name=name,
+            title=title,
+            description=description,
+            annotations=annotations,
+            icons=icons,
+            meta=meta,
+            structured_output=structured_output,
+        )
+        existing = self._tools.get(tool.name)
+        if existing:
+            if self.warn_on_duplicate_tools:
+                logger.warning(f"Tool already exists: {tool.name}")
+            return existing
+        self._tools[tool.name] = tool
+        return tool
+
+    def remove_tool(self, name: str) -> None:
+        """Remove a tool by name."""
+        if name not in self._tools:
+            raise ToolError(f"Unknown tool: {name}")
+        del self._tools[name]
+
+    async def call_tool(
+        self,
+        name: str,
+        arguments: dict[str, Any],
+        context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,
+        convert_result: bool = False,
+    ) -> Any:
+        """Call a tool by name with arguments."""
+        tool = self.get_tool(name)
+        if not tool:
+            raise ToolError(f"Unknown tool: {name}")
+
+        return await tool.run(arguments, context=context, convert_result=convert_result)

src/mcp/server/mcpserver/utilities/__init__.py

@@ -0,0 +1 @@
+"""MCPServer utility modules."""