Update middleware imports and documentation

CLAUDE.md

@@ -1,5 +1,9 @@
 # FastMCP Development Guidelines
 
+## Git
+
+This project uses `pre-commit` to run checks on all commits. If your commit doesn't pass the checks, it will not be created. Do not attempt to amend commits to pass checks.
+
 ## Documentation
 
 - Documentation uses the Mintlify framework

docs/servers/middleware.mdx

@@ -181,7 +181,7 @@ class ComponentAccessMiddleware(Middleware):
 
 ### Working with Listing Results
 
-For listing operations, you can inspect and modify the FastMCP components directly:
+For listing operations, the middleware `call_next` function returns a special object that contains the full list of FastMCP components prior to being converted to MCP format. You can modify this object and return it to the client. Specifically, the `ListToolsResult`, `ListResourcesResult`, `ListResourceTemplatesResult`, and `ListPromptsResult` objects can all be imported from fastmcp.server.middleware for this purpose. For example:
 
 ```python
 from fastmcp.server.middleware import Middleware, MiddlewareContext, ListToolsResult

src/fastmcp/server/middleware/__init__.py

@@ -1,6 +1,19 @@
-from .middleware import Middleware, MiddlewareContext
+from .middleware import (
+    Middleware,
+    MiddlewareContext,
+    CallNext,
+    ListToolsResult,
+    ListResourcesResult,
+    ListResourceTemplatesResult,
+    ListPromptsResult,
+)
 
 __all__ = [
     "Middleware",
     "MiddlewareContext",
+    "CallNext",
+    "ListToolsResult",
+    "ListResourcesResult",
+    "ListResourceTemplatesResult",
+    "ListPromptsResult",
 ]

src/fastmcp/server/middleware/middleware.py

@@ -25,6 +25,16 @@ from fastmcp.tools.tool import Tool
 if TYPE_CHECKING:
     from fastmcp.server.context import Context
 
+__all__ = [
+    "Middleware",
+    "MiddlewareContext",
+    "CallNext",
+    "ListToolsResult",
+    "ListResourcesResult",
+    "ListResourceTemplatesResult",
+    "ListPromptsResult",
+]
+
 logger = logging.getLogger(__name__)
 
 
@@ -52,12 +62,6 @@ ServerResultT = TypeVar(
 )
 
 
-@dataclass(kw_only=True)
-class CallToolResult:
-    content: list[mt.Content]
-    isError: bool = False
-
-
 @dataclass(kw_only=True)
 class ListToolsResult:
     tools: dict[str, Tool]