Permit empty prefixes

src/fastmcp/prompts/prompt_manager.py

@@ -11,20 +11,23 @@ class PromptManager(BasePromptManager):
     Adds ability to import prompts from other managers with prefixed names.
     """
 
-    def import_prompts(self, manager: "PromptManager", prefix: str) -> None:
+    def import_prompts(
+        self, manager: "PromptManager", prefix: str | None = None
+    ) -> None:
         """
         Import all prompts from another PromptManager with prefixed names.
 
         Args:
             manager: Another PromptManager instance to import prompts from
             prefix: Prefix to add to prompt names. The resulting prompt name will
-                   be in the format "{prefix}/{original_name}"
-                   For example, with prefix "weather" and prompt "forecast_prompt",
+                   be in the format "{prefix}{original_name}" if prefix is provided,
+                   otherwise the original name is used.
+                   For example, with prefix "weather/" and prompt "forecast_prompt",
                    the imported prompt would be available as "weather/forecast_prompt"
         """
         for name, prompt in manager._prompts.items():
             # Create prefixed name - we keep the original name in the Prompt object
-            prefixed_name = f"{prefix}/{name}"
+            prefixed_name = f"{prefix}{name}" if prefix else name
 
             # Log the import
             logger.debug(f"Importing prompt with name {name} as {prefixed_name}")

src/fastmcp/resources/resource_manager.py

@@ -10,20 +10,25 @@ logger = logging.getLogger(__name__)
 class ResourceManager(BaseResourceManager):
     """ResourceManager that adds methods to import resources from other managers."""
 
-    def import_resources(self, manager: "ResourceManager", prefix: str) -> None:
+    def import_resources(
+        self, manager: "ResourceManager", prefix: str | None = None
+    ) -> None:
         """Import resources from another resource manager.
 
-        Resources are imported with a prefixed URI. For example, if a resource has
-        URI "data://users" and you import it with prefix "app", the imported resource
-        will have URI "app+data://users".
+        Resources are imported with a prefixed URI if a prefix is provided. For example,
+        if a resource has URI "data://users" and you import it with prefix "app+", the
+        imported resource will have URI "app+data://users". If no prefix is provided,
+        the original URI is used.
 
         Args:
             manager: The ResourceManager to import from
-            prefix: A prefix to apply to the resource URIs
+            prefix: A prefix to apply to the resource URIs, including the delimiter.
+                   For example, "app+" would result in URIs like "app+data://users".
+                   If None, the original URI is used.
         """
         for uri, resource in manager._resources.items():
             # Create prefixed URI and copy the resource with the new URI
-            prefixed_uri = f"{prefix}+{uri}"
+            prefixed_uri = f"{prefix}{uri}" if prefix else uri
 
             # Log the import
             logger.debug(f"Importing resource with URI {uri} as {prefixed_uri}")
@@ -31,20 +36,27 @@ class ResourceManager(BaseResourceManager):
             # Store directly in resources dictionary
             self._resources[prefixed_uri] = resource
 
-    def import_templates(self, manager: "ResourceManager", prefix: str) -> None:
+    def import_templates(
+        self, manager: "ResourceManager", prefix: str | None = None
+    ) -> None:
         """Import resource templates from another resource manager.
 
-        Templates are imported with a prefixed URI template. For example, if a template has
-        URI template "data://users/{id}" and you import it with prefix "app", the
-        imported template will have URI template "app+data://users/{id}".
+        Templates are imported with a prefixed URI template if a prefix is provided.
+        For example, if a template has URI template "data://users/{id}" and you import
+        it with prefix "app+", the imported template will have URI template
+        "app+data://users/{id}". If no prefix is provided, the original URI template is used.
 
         Args:
             manager: The ResourceManager to import templates from
-            prefix: A prefix to apply to the template URIs
+            prefix: A prefix to apply to the template URIs, including the delimiter.
+                   For example, "app+" would result in URI templates like "app+data://users/{id}".
+                   If None, the original URI template is used.
         """
         for uri_template, template in manager._templates.items():
             # Create prefixed URI template and copy the template with the new URI template
-            prefixed_uri_template = f"{prefix}+{uri_template}"
+            prefixed_uri_template = (
+                f"{prefix}{uri_template}" if prefix else uri_template
+            )
 
             # Log the import
             logger.debug(

src/fastmcp/server/server.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict
+from typing import TYPE_CHECKING, Any, Dict
 
 import mcp.server.fastmcp
 import mcp.types
@@ -9,6 +9,9 @@ from fastmcp.server.context import Context
 from fastmcp.tools.tool_manager import ToolManager
 from fastmcp.utilities.logging import get_logger
 
+if TYPE_CHECKING:
+    pass
+
 logger = get_logger(__name__)
 
 
@@ -62,20 +65,21 @@ class FastMCP(mcp.server.fastmcp.FastMCP):
         # Mount the app in the list of mounted apps
         self._mounted_apps[prefix] = app
 
-        # Import tools from the mounted app
-        self._tool_manager.import_tools(app._tool_manager, prefix)
-
-        # Import resources from the mounted app
-        self._resource_manager.import_resources(app._resource_manager, prefix)
+        # Import tools from the mounted app with / delimiter
+        tool_prefix = f"{prefix}/"
+        self._tool_manager.import_tools(app._tool_manager, tool_prefix)
 
-        # Import resource templates
-        self._resource_manager.import_templates(app._resource_manager, prefix)
+        # Import resources and templates from the mounted app with + delimiter
+        resource_prefix = f"{prefix}+"
+        self._resource_manager.import_resources(app._resource_manager, resource_prefix)
+        self._resource_manager.import_templates(app._resource_manager, resource_prefix)
 
-        # Import prompts
-        self._prompt_manager.import_prompts(app._prompt_manager, prefix)
+        # Import prompts with / delimiter
+        prompt_prefix = f"{prefix}/"
+        self._prompt_manager.import_prompts(app._prompt_manager, prompt_prefix)
 
         logger.info(f"Mounted app with prefix '{prefix}'")
-        logger.debug(f"Imported tools with prefix '{prefix}/'")
-        logger.debug(f"Imported resources with prefix '{prefix}+'")
-        logger.debug(f"Imported templates with prefix '{prefix}+'")
-        logger.debug(f"Imported prompts with prefix '{prefix}/'")
+        logger.debug(f"Imported tools with prefix '{tool_prefix}'")
+        logger.debug(f"Imported resources with prefix '{resource_prefix}'")
+        logger.debug(f"Imported templates with prefix '{resource_prefix}'")
+        logger.debug(f"Imported prompts with prefix '{prompt_prefix}'")

src/fastmcp/tools/tool_manager.py

@@ -12,19 +12,22 @@ class ToolManager(mcp.server.fastmcp.tools.ToolManager):
     Adds ability to import tools from other managers with prefixed names.
     """
 
-    def import_tools(self, tool_manager: "ToolManager", prefix: str) -> None:
+    def import_tools(
+        self, tool_manager: "ToolManager", prefix: str | None = None
+    ) -> None:
         """
         Import all tools from another ToolManager with prefixed names.
 
         Args:
             tool_manager: Another ToolManager instance to import tools from
-            prefix: Prefix to add to tool names. The resulting tool name will
-                   be in the format "{prefix}/{original_name}"
-                   For example, with prefix "weather" and tool "forecast",
+            prefix: Prefix to add to tool names, including the delimiter.
+                   The resulting tool name will be in the format "{prefix}{original_name}"
+                   if prefix is provided, otherwise the original name is used.
+                   For example, with prefix "weather/" and tool "forecast",
                    the imported tool would be available as "weather/forecast"
         """
         for name, tool in tool_manager._tools.items():
-            prefixed_name = f"{prefix}/{name}"
+            prefixed_name = f"{prefix}{name}" if prefix else name
 
             # Create a shallow copy of the tool with the prefixed name
             copied_tool = Tool.from_function(

tests/prompts/test_prompt_manager.py

@@ -44,7 +44,7 @@ def test_import_prompts():
     target_manager = PromptManager()
 
     # Import prompts from source to target
-    prefix = "nlp"
+    prefix = "nlp/"
     target_manager.import_prompts(source_manager, prefix)
 
     # Verify prompts were imported with prefixes
@@ -109,7 +109,7 @@ def test_import_prompts_with_duplicates():
     target_manager._prompts["common"] = target_prompt
 
     # Import prompts with prefix
-    prefix = "external"
+    prefix = "external/"
     target_manager.import_prompts(source_manager, prefix)
 
     # Verify both prompts exist in target manager
@@ -146,10 +146,10 @@ def test_import_prompts_with_nested_prefixes():
     first_manager._prompts["analyze"] = original_prompt
 
     # Import to second manager with prefix
-    second_manager.import_prompts(first_manager, "text")
+    second_manager.import_prompts(first_manager, "text/")
 
     # Import from second to third with another prefix
-    third_manager.import_prompts(second_manager, "ai")
+    third_manager.import_prompts(second_manager, "ai/")
 
     # Verify the nested prefixing
     assert "text/analyze" in second_manager._prompts

tests/resources/test_resource_manager.py

@@ -39,7 +39,7 @@ def test_import_resources():
     target_manager = ResourceManager()
 
     # Import resources from source to target
-    prefix = "data"
+    prefix = "data+"
     target_manager.import_resources(source_manager, prefix)
 
     # Verify resources were imported with prefixes
@@ -126,7 +126,7 @@ def test_import_templates():
     target_manager = ResourceManager()
 
     # Import templates from source to target
-    prefix = "shop"
+    prefix = "shop+"
     target_manager.import_templates(source_manager, prefix)
 
     # Verify templates were imported with prefixes
@@ -212,7 +212,7 @@ def test_import_multiple_resource_types():
     target_manager = ResourceManager()
 
     # Import both resources and templates
-    prefix = "test"
+    prefix = "test+"
     target_manager.import_resources(source_manager, prefix)
     target_manager.import_templates(source_manager, prefix)
 

tests/tools/test_tool_manager.py

@@ -23,7 +23,7 @@ def test_import_tools():
     target_manager = ToolManager()
 
     # Import tools from source to target
-    prefix = "source"
+    prefix = "source/"
     target_manager.import_tools(source_manager, prefix)
 
     # Verify tools were imported with prefixes
@@ -65,7 +65,7 @@ def test_tool_duplicate_behavior():
     )  # Pre-create with the prefixed name
 
     # Import tools from source to target
-    target_manager.import_tools(source_manager, "source")
+    target_manager.import_tools(source_manager, "source/")
 
     # The original tool in the target manager is replaced by the imported one
     assert target_manager._tools["source/common_tool"].fn.__name__ == source_fn.__name__
@@ -89,8 +89,8 @@ def test_import_tools_with_multiple_prefixes():
 
     # Create target manager and import from both sources
     main_manager = ToolManager()
-    main_manager.import_tools(weather_manager, "weather")
-    main_manager.import_tools(news_manager, "news")
+    main_manager.import_tools(weather_manager, "weather/")
+    main_manager.import_tools(news_manager, "news/")
 
     # Verify tools were imported with correct prefixes
     assert "weather/forecast" in main_manager._tools