Refactor FastMCP to inherit from Provider

src/fastmcp/contrib/component_manager/component_service.py

@@ -188,10 +188,14 @@ async def _enable_resource(self, uri: str) -> Resource | ResourceTemplate:
         if resource_keys:
             self._server.enable(keys=resource_keys)
             resource = await self._server.get_resource(uri)
+            if resource is None:
+                raise NotFoundError(f"Resource {uri!r} not found after enabling")
             return resource
         if template_keys:
             self._server.enable(keys=template_keys)
             template = await self._server.get_resource_template(uri)
+            if template is None:
+                raise NotFoundError(f"Template {uri!r} not found after enabling")
             return template
 
         # 2. Check mounted servers via FastMCPProvider
@@ -234,11 +238,15 @@ async def _disable_resource(self, uri: str) -> Resource | ResourceTemplate:
         if resource_keys:
             # Get the highest version to return before disabling
             resource = await self._server.get_resource(uri)
+            if resource is None:
+                raise NotFoundError(f"Resource {uri!r} not found")
             self._server.disable(keys=resource_keys)
             return resource
         if template_keys:
             # Get the highest version to return before disabling
             template = await self._server.get_resource_template(uri)
+            if template is None:
+                raise NotFoundError(f"Template {uri!r} not found")
             self._server.disable(keys=template_keys)
             return template
 

src/fastmcp/server/middleware/authorization.py

@@ -28,7 +28,7 @@
 
 import mcp.types as mt
 
-from fastmcp.exceptions import AuthorizationError, NotFoundError
+from fastmcp.exceptions import AuthorizationError
 from fastmcp.prompts.prompt import Prompt, PromptResult
 from fastmcp.resources.resource import Resource, ResourceResult
 from fastmcp.resources.template import ResourceTemplate
@@ -136,7 +136,12 @@ async def on_call_tool(
                 f"Authorization failed for tool '{tool_name}': missing context"
             )
 
+        # Resolve tool (includes component-level auth check)
         tool = await fastmcp.fastmcp.get_tool(tool_name)
+        if tool is None:
+            raise AuthorizationError(
+                f"Authorization failed for tool '{tool_name}': tool not found"
+            )
 
         token = get_access_token()
         ctx = AuthContext(token=token, component=tool)
@@ -196,11 +201,14 @@ async def on_read_resource(
                 f"Authorization failed for resource '{uri}': missing context"
             )
 
-        # Try concrete resource first, then template (for template-backed URIs)
-        try:
-            component = await fastmcp.fastmcp.get_resource(str(uri))
-        except NotFoundError:
+        # Try concrete resource first, then template (includes component-level auth check)
+        component = await fastmcp.fastmcp.get_resource(str(uri))
+        if component is None:
             component = await fastmcp.fastmcp.get_resource_template(str(uri))
+        if component is None:
+            raise AuthorizationError(
+                f"Authorization failed for resource '{uri}': resource not found"
+            )
 
         token = get_access_token()
         ctx = AuthContext(token=token, component=component)
@@ -286,7 +294,12 @@ async def on_get_prompt(
                 f"Authorization failed for prompt '{prompt_name}': missing context"
             )
 
+        # Resolve prompt (includes component-level auth check)
         prompt = await fastmcp.fastmcp.get_prompt(prompt_name)
+        if prompt is None:
+            raise AuthorizationError(
+                f"Authorization failed for prompt '{prompt_name}': prompt not found"
+            )
 
         token = get_access_token()
         ctx = AuthContext(token=token, component=prompt)

src/fastmcp/server/providers/__init__.py

@@ -27,6 +27,7 @@ async def get_tool(self, name: str) -> Tool | None:
 
 from typing import TYPE_CHECKING
 
+from fastmcp.server.providers.aggregate import AggregateProvider
 from fastmcp.server.providers.base import Provider
 from fastmcp.server.providers.fastmcp_provider import FastMCPProvider
 from fastmcp.server.providers.filesystem import FileSystemProvider
@@ -37,6 +38,7 @@ async def get_tool(self, name: str) -> Tool | None:
     from fastmcp.server.providers.proxy import ProxyProvider as ProxyProvider
 
 __all__ = [
+    "AggregateProvider",
     "FastMCPProvider",
     "FileSystemProvider",
     "LocalProvider",

src/fastmcp/server/providers/aggregate.py

@@ -1,8 +1,19 @@
 """AggregateProvider for combining multiple providers into one.
 
-This module provides `AggregateProvider` which presents multiple providers
-as a single unified provider. Used internally by FastMCP for aggregating
-components from all providers.
+This module provides `AggregateProvider`, a utility class that presents
+multiple providers as a single unified provider. Useful when you want to
+combine custom providers without creating a full FastMCP server.
+
+Example:
+    ```python
+    from fastmcp.server.providers import AggregateProvider
+
+    # Combine multiple providers into one
+    combined = AggregateProvider([provider1, provider2, provider3])
+
+    # Use like any other provider
+    tools = await combined.list_tools()
+    ```
 """
 
 from __future__ import annotations
@@ -28,12 +39,15 @@
 
 
 class AggregateProvider(Provider):
-    """Presents multiple providers as a single provider.
+    """Utility provider that combines multiple providers into one.
 
     Components are aggregated from all providers. For get_* operations,
     providers are queried in parallel and the highest version is returned.
 
     Errors from individual providers are logged and skipped (graceful degradation).
+
+    This is useful when you want to combine custom providers without creating
+    a full FastMCP server.
     """
 
     def __init__(self, providers: Sequence[Provider]) -> None:

src/fastmcp/server/providers/base.py

@@ -65,13 +65,17 @@ class Provider:
     """
 
     def __init__(self) -> None:
-        # Visibility is the first (innermost) transform - closest to the base provider
         self._visibility = Visibility()
-        self._transforms: list[Transform] = [self._visibility]
+        self._transforms: list[Transform] = []
 
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}()"
 
+    @property
+    def transforms(self) -> list[Transform]:
+        """All transforms including visibility (applied last/outermost)."""
+        return [*self._transforms, self._visibility]
+
     def add_transform(self, transform: Transform) -> None:
         """Add a transform to this provider.
 
@@ -110,7 +114,7 @@ async def base() -> Sequence[Tool]:
             return await self.list_tools()
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.list_tools, call_next=chain)
 
         return await chain()
@@ -132,7 +136,7 @@ async def base(n: str, version: VersionSpec | None = None) -> Tool | None:
             return await self.get_tool(n, version)
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.get_tool, call_next=chain)
 
         return await chain(name, version=version)
@@ -144,7 +148,7 @@ async def base() -> Sequence[Resource]:
             return await self.list_resources()
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.list_resources, call_next=chain)
 
         return await chain()
@@ -163,7 +167,7 @@ async def base(u: str, version: VersionSpec | None = None) -> Resource | None:
             return await self.get_resource(u, version)
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.get_resource, call_next=chain)
 
         return await chain(uri, version=version)
@@ -175,7 +179,7 @@ async def base() -> Sequence[ResourceTemplate]:
             return await self.list_resource_templates()
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.list_resource_templates, call_next=chain)
 
         return await chain()
@@ -196,7 +200,7 @@ async def base(
             return await self.get_resource_template(u, version)
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.get_resource_template, call_next=chain)
 
         return await chain(uri, version=version)
@@ -208,7 +212,7 @@ async def base() -> Sequence[Prompt]:
             return await self.list_prompts()
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.list_prompts, call_next=chain)
 
         return await chain()
@@ -227,7 +231,7 @@ async def base(n: str, version: VersionSpec | None = None) -> Prompt | None:
             return await self.get_prompt(n, version)
 
         chain = base
-        for transform in self._transforms:
+        for transform in self.transforms:
             chain = partial(transform.get_prompt, call_next=chain)
 
         return await chain(name, version=version)
@@ -402,13 +406,13 @@ async def templates_base() -> Sequence[ResourceTemplate]:
         async def prompts_base() -> Sequence[Prompt]:
             return prompts
 
-        # Apply transforms in order (first is innermost)
+        # Apply transforms in order (visibility last/outermost)
         tools_chain = tools_base
         resources_chain = resources_base
         templates_chain = templates_base
         prompts_chain = prompts_base
 
-        for transform in self._transforms:
+        for transform in self.transforms:
             tools_chain = partial(transform.list_tools, call_next=tools_chain)
             resources_chain = partial(
                 transform.list_resources, call_next=resources_chain

src/fastmcp/server/providers/fastmcp_provider.py

@@ -19,7 +19,6 @@
 import mcp.types
 from mcp.types import AnyUrl
 
-from fastmcp.exceptions import NotFoundError
 from fastmcp.prompts.prompt import Prompt, PromptResult
 from fastmcp.resources.resource import Resource, ResourceResult
 from fastmcp.resources.template import ResourceTemplate
@@ -486,9 +485,9 @@ def __init__(self, server: FastMCP[Any]):
     async def list_tools(self) -> Sequence[Tool]:
         """List all tools from the mounted server as FastMCPProviderTools.
 
-        Calls the nested server's middleware to list tools, then wraps
-        each tool as a FastMCPProviderTool that delegates execution to the
-        nested server's middleware.
+        Runs the mounted server's middleware so filtering/transformation applies.
+        Wraps each tool as a FastMCPProviderTool that delegates execution to
+        the nested server's middleware.
         """
         raw_tools = await self.server.get_tools(run_middleware=True)
         return [FastMCPProviderTool.wrap(self.server, t) for t in raw_tools]
@@ -501,9 +500,8 @@ async def get_tool(
         Passes the full VersionSpec to the nested server, which handles both
         exact version matching and range filtering.
         """
-        try:
-            raw_tool = await self.server.get_tool(name, version)
-        except NotFoundError:
+        raw_tool = await self.server.get_tool(name, version)
+        if raw_tool is None:
             return None
         return FastMCPProviderTool.wrap(self.server, raw_tool)
 
@@ -514,9 +512,9 @@ async def get_tool(
     async def list_resources(self) -> Sequence[Resource]:
         """List all resources from the mounted server as FastMCPProviderResources.
 
-        Calls the nested server's middleware to list resources, then wraps
-        each resource as a FastMCPProviderResource that delegates reading to the
-        nested server's middleware.
+        Runs the mounted server's middleware so filtering/transformation applies.
+        Wraps each resource as a FastMCPProviderResource that delegates reading
+        to the nested server's middleware.
         """
         raw_resources = await self.server.get_resources(run_middleware=True)
         return [FastMCPProviderResource.wrap(self.server, r) for r in raw_resources]
@@ -529,9 +527,8 @@ async def get_resource(
         Passes the full VersionSpec to the nested server, which handles both
         exact version matching and range filtering.
         """
-        try:
-            raw_resource = await self.server.get_resource(uri, version)
-        except NotFoundError:
+        raw_resource = await self.server.get_resource(uri, version)
+        if raw_resource is None:
             return None
         return FastMCPProviderResource.wrap(self.server, raw_resource)
 
@@ -542,6 +539,7 @@ async def get_resource(
     async def list_resource_templates(self) -> Sequence[ResourceTemplate]:
         """List all resource templates from the mounted server.
 
+        Runs the mounted server's middleware so filtering/transformation applies.
         Returns FastMCPProviderResourceTemplate instances that create
         FastMCPProviderResources when materialized.
         """
@@ -558,9 +556,8 @@ async def get_resource_template(
         Passes the full VersionSpec to the nested server, which handles both
         exact version matching and range filtering.
         """
-        try:
-            raw_template = await self.server.get_resource_template(uri, version)
-        except NotFoundError:
+        raw_template = await self.server.get_resource_template(uri, version)
+        if raw_template is None:
             return None
         return FastMCPProviderResourceTemplate.wrap(self.server, raw_template)
 
@@ -571,6 +568,7 @@ async def get_resource_template(
     async def list_prompts(self) -> Sequence[Prompt]:
         """List all prompts from the mounted server as FastMCPProviderPrompts.
 
+        Runs the mounted server's middleware so filtering/transformation applies.
         Returns FastMCPProviderPrompt instances that delegate rendering to the
         wrapped server's middleware.
         """
@@ -585,9 +583,8 @@ async def get_prompt(
         Passes the full VersionSpec to the nested server, which handles both
         exact version matching and range filtering.
         """
-        try:
-            raw_prompt = await self.server.get_prompt(name, version)
-        except NotFoundError:
+        raw_prompt = await self.server.get_prompt(name, version)
+        if raw_prompt is None:
             return None
         return FastMCPProviderPrompt.wrap(self.server, raw_prompt)
 
@@ -599,12 +596,12 @@ async def get_tasks(self) -> Sequence[FastMCPComponent]:
         """Return task-eligible components from the mounted server.
 
         Returns the child's ACTUAL components (not wrapped) so their actual
-        functions get registered with Docket. Uses _source_get_tasks() to get
-        components with child server's transforms applied, then applies this
-        provider's transforms for correct registration keys.
+        functions get registered with Docket. Gets components with child
+        server's transforms applied, then applies this provider's transforms
+        for correct registration keys.
         """
         # Get tasks with child server's transforms already applied
-        components = list(await self.server._source_get_tasks())
+        components = list(await self.server.get_tasks())
 
         # Separate by type for this provider's transform application
         tools = [c for c in components if isinstance(c, Tool)]