fix: Update prompt manager to support prefix filtering and URI-based storage

- Add prefix parameter to PromptManager.list_prompts() with path prefix behavior
- Add _normalize_to_uri() method to convert names to prompt:// URIs
- Update add_prompt() to use URIs as keys for consistent storage
- Update get_prompt() to accept both names and URIs
- Update FastMCP server to pass request object to lowlevel handlers
- Fix test expectation for new path prefix behavior in list_templates

This completes the implementation of consistent prefix-based filtering
across all list operations (resources, templates, tools, and prompts).

Author: Tapan Chugh

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

@@ -15,28 +15,43 @@ 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 _normalize_to_uri(self, name_or_uri: str) -> str:
+        """Convert name to URI if needed."""
+        if name_or_uri.startswith("prompt://"):
+            return name_or_uri
+        return f"prompt://{name_or_uri}"
 
-    def list_prompts(self) -> list[Prompt]:
-        """List all registered prompts."""
-        return list(self._prompts.values())
+    def get_prompt(self, name: str) -> Prompt | None:
+        """Get prompt by name or URI."""
+        uri = self._normalize_to_uri(name)
+        return self._prompts.get(uri)
+
+    def list_prompts(self, prefix: str | None = None) -> list[Prompt]:
+        """List all registered prompts, optionally filtered by URI prefix."""
+        prompts = list(self._prompts.values())
+        if prefix:
+            # Ensure prefix ends with / for proper path matching
+            if not prefix.endswith("/"):
+                prefix = prefix + "/"
+            prompts = [p for p in prompts if str(p.uri).startswith(prefix)]
+        logger.debug("Listing prompts", extra={"count": len(prompts), "prefix": prefix})
+        return prompts
 
     def add_prompt(
         self,
         prompt: Prompt,
     ) -> Prompt:
         """Add a prompt to the manager."""
-
+        logger.debug(f"Adding prompt: {prompt.name} with URI: {prompt.uri}")
+        
         # Check for duplicates
-        existing = self._prompts.get(prompt.name)
+        existing = self._prompts.get(prompt.uri)
         if existing:
             if self.warn_on_duplicate_prompts:
-                logger.warning(f"Prompt already exists: {prompt.name}")
+                logger.warning(f"Prompt already exists: {prompt.uri}")
             return existing
 
-        self._prompts[prompt.name] = prompt
+        self._prompts[prompt.uri] = prompt
         return prompt
 
     async def render_prompt(self, name: str, arguments: dict[str, Any] | None = None) -> list[Message]:

src/mcp/server/fastmcp/server.py

@@ -267,10 +267,10 @@ def _setup_handlers(self) -> None:
         self._mcp_server.get_prompt()(self.get_prompt)
         self._mcp_server.list_resource_templates()(self.list_resource_templates)
 
-    async def list_tools(self, request: types.ListToolsRequest) -> list[MCPTool]:
+    async def list_tools(self, request: types.ListToolsRequest | None = None) -> list[MCPTool]:
         """List all available tools, optionally filtered by prefix."""
         prefix = None
-        if request.params:
+        if request and request.params:
             prefix = request.params.prefix
         tools = self._tool_manager.list_tools(prefix=prefix)
         return [
@@ -969,10 +969,10 @@ def streamable_http_app(self) -> Starlette:
             lifespan=lambda app: self.session_manager.run(),
         )
 
-    async def list_prompts(self, request: types.ListPromptsRequest) -> list[MCPPrompt]:
+    async def list_prompts(self, request: types.ListPromptsRequest | None = None) -> list[MCPPrompt]:
         """List all available prompts, optionally filtered by prefix."""
         prefix = None
-        if request.params:
+        if request and request.params:
             prefix = request.params.prefix
         prompts = self._prompt_manager.list_prompts(prefix=prefix)
         return [

src/mcp/server/lowlevel/server.py

@@ -415,7 +415,7 @@ async def _get_cached_tool_definition(self, tool_name: str) -> types.Tool | None
         if tool_name not in self._tool_cache:
             if types.ListToolsRequest in self.request_handlers:
                 logger.debug("Tool cache miss for %s, refreshing cache", tool_name)
-                await self.request_handlers[types.ListToolsRequest](None)
+                await self.request_handlers[types.ListToolsRequest](types.ListToolsRequest(method="tools/list"))
 
         tool = self._tool_cache.get(tool_name)
         if tool is None:

tests/server/fastmcp/resources/test_resource_manager.py

@@ -219,11 +219,10 @@ def product_func(product_id: str) -> str:
         assert len(user_123_templates) == 1
         assert template2 in user_123_templates  # users/{user_id}/posts/{post_id} matches
 
-        # Without trailing slash, both match
+        # Without trailing slash, it gets added automatically so only posts template matches
         user_123_no_slash = manager.list_templates(prefix="http://api.com/users/123")
-        assert len(user_123_no_slash) == 2
-        assert template1 in user_123_no_slash
-        assert template2 in user_123_no_slash
+        assert len(user_123_no_slash) == 1
+        assert template2 in user_123_no_slash  # Only posts template has path after users/123/
 
         # Test product prefix
         product_templates = manager.list_templates(prefix="http://api.com/products/")