Add icons support for ResourceTemplate (#1412)

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

@@ -10,6 +10,7 @@ from pydantic import AnyUrl
 from mcp.server.fastmcp.resources.base import Resource
 from mcp.server.fastmcp.resources.templates import ResourceTemplate
 from mcp.server.fastmcp.utilities.logging import get_logger
+from mcp.types import Icon
 
 if TYPE_CHECKING:
     from mcp.server.fastmcp.server import Context
@@ -61,6 +62,7 @@ class ResourceManager:
         title: str | None = None,
         description: str | None = None,
         mime_type: str | None = None,
+        icons: list[Icon] | None = None,
     ) -> ResourceTemplate:
         """Add a template from a function."""
         template = ResourceTemplate.from_function(
@@ -70,6 +72,7 @@ class ResourceManager:
             title=title,
             description=description,
             mime_type=mime_type,
+            icons=icons,
         )
         self._templates[template.uri_template] = template
         return template

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

@@ -12,6 +12,7 @@ from pydantic import BaseModel, Field, validate_call
 from mcp.server.fastmcp.resources.types import FunctionResource, Resource
 from mcp.server.fastmcp.utilities.context_injection import find_context_parameter, inject_context
 from mcp.server.fastmcp.utilities.func_metadata import func_metadata
+from mcp.types import Icon
 
 if TYPE_CHECKING:
     from mcp.server.fastmcp.server import Context
@@ -27,6 +28,7 @@ class ResourceTemplate(BaseModel):
     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")
     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")
@@ -40,6 +42,7 @@ class ResourceTemplate(BaseModel):
         title: str | None = None,
         description: str | None = None,
         mime_type: str | None = None,
+        icons: list[Icon] | None = None,
         context_kwarg: str | None = None,
     ) -> ResourceTemplate:
         """Create a template from a function."""
@@ -67,6 +70,7 @@ class ResourceTemplate(BaseModel):
             title=title,
             description=description or fn.__doc__ or "",
             mime_type=mime_type or "text/plain",
+            icons=icons,
             fn=fn,
             parameters=parameters,
             context_kwarg=context_kwarg,
@@ -103,7 +107,7 @@ class ResourceTemplate(BaseModel):
                 title=self.title,
                 description=self.description,
                 mime_type=self.mime_type,
-                icons=None,  # Resource templates don't support icons
+                icons=self.icons,
                 fn=lambda: result,  # Capture result in closure
             )
         except Exception as e:

src/mcp/server/fastmcp/server.py

@@ -335,6 +335,7 @@ class FastMCP(Generic[LifespanResultT]):
                 title=template.title,
                 description=template.description,
                 mimeType=template.mime_type,
+                icons=template.icons,
             )
             for template in templates
         ]
@@ -559,7 +560,7 @@ class FastMCP(Generic[LifespanResultT]):
                     title=title,
                     description=description,
                     mime_type=mime_type,
-                    # Note: Resource templates don't support icons
+                    icons=icons,
                 )
             else:
                 # Register as regular resource

src/mcp/types.py

@@ -470,6 +470,8 @@ class ResourceTemplate(BaseMetadata):
     The MIME type for all resources that match this template. This should only be
     included if all resources matching this template have the same type.
     """
+    icons: list[Icon] | None = None
+    """An optional list of icons for this resource template."""
     annotations: Annotations | None = None
     meta: dict[str, Any] | None = Field(alias="_meta", default=None)
     """