fix: add status field in Resource class and Resource as a return type in CallToolResult

Author: bzsurbhi

src/mcp/__init__.py

@@ -38,6 +38,7 @@
     ReadResourceResult,
     Resource,
     ResourcesCapability,
+    ResourceStatus,
     ResourceUpdatedNotification,
     RootsCapability,
     SamplingMessage,
@@ -90,6 +91,7 @@
     "ReadResourceRequest",
     "ReadResourceResult",
     "ResourcesCapability",
+    "ResourceStatus",
     "ResourceUpdatedNotification",
     "Resource",
     "RootsCapability",

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

@@ -13,6 +13,8 @@
     field_validator,
 )
 
+from mcp.types import ResourceStatus as MCPResourceStatus
+
 
 class Resource(BaseModel, abc.ABC):
     """Base class for all resources."""
@@ -31,6 +33,10 @@ class Resource(BaseModel, abc.ABC):
         description="MIME type of the resource content",
         pattern=r"^[a-zA-Z0-9]+/[a-zA-Z0-9\-+.]+$",
     )
+    status: MCPResourceStatus = Field(
+        default=MCPResourceStatus.PENDING,
+        description="Status of the resource",
+    )
 
     @field_validator("name", mode="before")
     @classmethod

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

@@ -89,6 +89,22 @@ def list_resources(self) -> list[Resource]:
         logger.debug("Listing resources", extra={"count": len(self._resources)})
         return list(self._resources.values())
 
+    def update_resource(self, resource: Resource) -> Resource:
+        """Update an existing resource."""
+        logger.debug(
+            "Updating resource",
+            extra={
+                "uri": resource.uri,
+                "type": type(resource).__name__,
+                "status": resource.status,
+                "resource_name": resource.name,
+            },
+        )
+        if str(resource.uri) not in self._resources:
+            raise ValueError(f"Resource not found: {resource.uri}")
+        self._resources[str(resource.uri)] = resource
+        return resource
+
     def list_templates(self) -> list[ResourceTemplate]:
         """List all registered templates."""
         logger.debug("Listing templates", extra={"count": len(self._templates)})

src/mcp/server/fastmcp/server.py

@@ -269,7 +269,7 @@ def get_context(self) -> Context[ServerSession, object]:
 
     async def call_tool(
         self, name: str, arguments: dict[str, Any]
-    ) -> Sequence[TextContent | ImageContent | EmbeddedResource]:
+    ) -> Sequence[TextContent | ImageContent | EmbeddedResource | MCPResource]:
         """Call a tool by name with arguments."""
         context = self.get_context()
         result = await self._tool_manager.call_tool(name, arguments, context=context)
@@ -282,10 +282,12 @@ async def list_resources(self) -> list[MCPResource]:
         resources = self._resource_manager.list_resources()
         return [
             MCPResource(
+                type="resource",
                 uri=resource.uri,
                 name=resource.name or "",
                 description=resource.description,
                 mimeType=resource.mime_type,
+                status=resource.status,
             )
             for resource in resources
         ]
@@ -869,7 +871,7 @@ async def get_prompt(
 
 def _convert_to_content(
     result: Any,
-) -> Sequence[TextContent | ImageContent | EmbeddedResource]:
+) -> Sequence[TextContent | ImageContent | EmbeddedResource | MCPResource]:
     """Convert a result to a sequence of content objects."""
     if result is None:
         return []

src/mcp/server/lowlevel/server.py

@@ -399,7 +399,10 @@ def decorator(
                 ...,
                 Awaitable[
                     Iterable[
-                        types.TextContent | types.ImageContent | types.EmbeddedResource
+                        types.TextContent
+                        | types.ImageContent
+                        | types.EmbeddedResource
+                        | types.Resource
                     ]
                 ],
             ],

src/mcp/types.py

@@ -1,4 +1,5 @@
 from collections.abc import Callable
+from enum import Enum
 from typing import (
     Annotated,
     Any,
@@ -368,15 +369,31 @@ class Annotations(BaseModel):
     model_config = ConfigDict(extra="allow")
 
 
+class ResourceStatus(str, Enum):
+    """The status of a resource."""
+
+    READY = "ready"
+    """Resource is ready to be read."""
+    PENDING = "pending"
+    """Resource is being created or processed."""
+    ERROR = "error"
+    """Resource has an error state."""
+    DELETED = "deleted"
+    """Resource has been deleted."""
+
+
 class Resource(BaseModel):
     """A known resource that the server is capable of reading."""
 
+    type: Literal["resource"]
     uri: Annotated[AnyUrl, UrlConstraints(host_required=False)]
     """The URI of this resource."""
     name: str
     """A human-readable name for this resource."""
     description: str | None = None
     """A description of what this resource represents."""
+    status: ResourceStatus | None = None
+    """The status of this resource."""
     mimeType: str | None = None
     """The MIME type of this resource, if known."""
     size: int | None = None
@@ -791,7 +808,7 @@ class CallToolRequest(Request[CallToolRequestParams, Literal["tools/call"]]):
 class CallToolResult(Result):
     """The server's response to a tool call."""
 
-    content: list[TextContent | ImageContent | EmbeddedResource]
+    content: list[TextContent | ImageContent | EmbeddedResource | Resource]
     isError: bool = False
 
 

tests/issues/test_152_resource_mime_type.py

@@ -83,12 +83,16 @@ async def test_lowlevel_resource_mime_type():
     # Create test resources with specific mime types
     test_resources = [
         types.Resource(
-            uri=AnyUrl("test://image"), name="test image", mimeType="image/png"
+            uri=AnyUrl("test://image"),
+            name="test image",
+            mimeType="image/png",
+            type="resource",
         ),
         types.Resource(
             uri=AnyUrl("test://image_bytes"),
             name="test image bytes",
             mimeType="image/png",
+            type="resource",
         ),
     ]
 

tests/shared/test_memory.py

@@ -24,6 +24,7 @@ async def handle_list_resources():
                 uri=AnyUrl("memory://test"),
                 name="Test Resource",
                 description="A test resource",
+                type="resource",
             )
         ]