Move Prompt object instantiation from server to prompt manager

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

@@ -4,6 +4,7 @@
 
 from mcp.server.fastmcp.prompts.base import Message, Prompt
 from mcp.server.fastmcp.utilities.logging import get_logger
+from mcp.types import AnyFunction
 
 logger = get_logger(__name__)
 
@@ -25,9 +26,18 @@ def list_prompts(self) -> list[Prompt]:
 
     def add_prompt(
         self,
-        prompt: Prompt,
+        fn: AnyFunction,
+        name: str | None = None,
+        description: str | None = None,
     ) -> Prompt:
-        """Add a prompt to the manager."""
+        """Add a prompt to the manager.
+
+        Args:
+            fn: Function to create a prompt from
+            name: Optional name for the prompt
+            description: Optional description of the prompt
+        """
+        prompt = Prompt.from_function(fn, name=name, description=description)
 
         # Check for duplicates
         existing = self._prompts.get(prompt.name)

src/mcp/server/fastmcp/server.py

@@ -35,7 +35,7 @@
     AuthSettings,
 )
 from mcp.server.fastmcp.exceptions import ResourceError
-from mcp.server.fastmcp.prompts import Prompt, PromptManager
+from mcp.server.fastmcp.prompts import PromptManager
 from mcp.server.fastmcp.resources import FunctionResource, Resource, ResourceManager
 from mcp.server.fastmcp.tools import ToolManager
 from mcp.server.fastmcp.utilities.logging import configure_logging, get_logger
@@ -138,8 +138,9 @@ def __init__(
         self,
         name: str | None = None,
         instructions: str | None = None,
-        auth_server_provider: OAuthAuthorizationServerProvider[Any, Any, Any]
-        | None = None,
+        auth_server_provider: (
+            OAuthAuthorizationServerProvider[Any, Any, Any] | None
+        ) = None,
         event_store: EventStore | None = None,
         **settings: Any,
     ):
@@ -148,9 +149,11 @@ def __init__(
         self._mcp_server = MCPServer(
             name=name or "FastMCP",
             instructions=instructions,
-            lifespan=lifespan_wrapper(self, self.settings.lifespan)
-            if self.settings.lifespan
-            else default_lifespan,
+            lifespan=(
+                lifespan_wrapper(self, self.settings.lifespan)
+                if self.settings.lifespan
+                else default_lifespan
+            ),
         )
         self._tool_manager = ToolManager(
             warn_on_duplicate_tools=self.settings.warn_on_duplicate_tools
@@ -481,13 +484,20 @@ def decorator(fn: AnyFunction) -> AnyFunction:
 
         return decorator
 
-    def add_prompt(self, prompt: Prompt) -> None:
+    def add_prompt(
+        self,
+        fn: AnyFunction,
+        name: str | None = None,
+        description: str | None = None,
+    ) -> None:
         """Add a prompt to the server.
 
         Args:
-            prompt: A Prompt instance to add
+            fn: Function to create a prompt from
+            name: Optional name for the prompt
+            description: Optional description of the prompt
         """
-        self._prompt_manager.add_prompt(prompt)
+        self._prompt_manager.add_prompt(fn, name=name, description=description)
 
     def prompt(
         self, name: str | None = None, description: str | None = None
@@ -533,8 +543,7 @@ async def analyze_file(path: str) -> list[Message]:
             )
 
         def decorator(func: AnyFunction) -> AnyFunction:
-            prompt = Prompt.from_function(func, name=name, description=description)
-            self.add_prompt(prompt)
+            self.add_prompt(func, name=name, description=description)
             return func
 
         return decorator

tests/server/fastmcp/prompts/test_manager.py

@@ -12,10 +12,10 @@ def fn() -> str:
             return "Hello, world!"
 
         manager = PromptManager()
-        prompt = Prompt.from_function(fn)
-        added = manager.add_prompt(prompt)
-        assert added == prompt
-        assert manager.get_prompt("fn") == prompt
+        added = manager.add_prompt(fn)
+        assert isinstance(added, Prompt)
+        assert added.name == "fn"
+        assert manager.get_prompt("fn") == added
 
     def test_add_duplicate_prompt(self, caplog):
         """Test adding the same prompt twice."""
@@ -24,9 +24,8 @@ def fn() -> str:
             return "Hello, world!"
 
         manager = PromptManager()
-        prompt = Prompt.from_function(fn)
-        first = manager.add_prompt(prompt)
-        second = manager.add_prompt(prompt)
+        first = manager.add_prompt(fn)
+        second = manager.add_prompt(fn)
         assert first == second
         assert "Prompt already exists" in caplog.text
 
@@ -37,9 +36,8 @@ def fn() -> str:
             return "Hello, world!"
 
         manager = PromptManager(warn_on_duplicate_prompts=False)
-        prompt = Prompt.from_function(fn)
-        first = manager.add_prompt(prompt)
-        second = manager.add_prompt(prompt)
+        first = manager.add_prompt(fn)
+        second = manager.add_prompt(fn)
         assert first == second
         assert "Prompt already exists" not in caplog.text
 
@@ -53,10 +51,8 @@ def fn2() -> str:
             return "Goodbye, world!"
 
         manager = PromptManager()
-        prompt1 = Prompt.from_function(fn1)
-        prompt2 = Prompt.from_function(fn2)
-        manager.add_prompt(prompt1)
-        manager.add_prompt(prompt2)
+        prompt1 = manager.add_prompt(fn1)
+        prompt2 = manager.add_prompt(fn2)
         prompts = manager.list_prompts()
         assert len(prompts) == 2
         assert prompts == [prompt1, prompt2]
@@ -69,8 +65,7 @@ def fn() -> str:
             return "Hello, world!"
 
         manager = PromptManager()
-        prompt = Prompt.from_function(fn)
-        manager.add_prompt(prompt)
+        manager.add_prompt(fn)
         messages = await manager.render_prompt("fn")
         assert messages == [
             UserMessage(content=TextContent(type="text", text="Hello, world!"))
@@ -84,8 +79,7 @@ def fn(name: str) -> str:
             return f"Hello, {name}!"
 
         manager = PromptManager()
-        prompt = Prompt.from_function(fn)
-        manager.add_prompt(prompt)
+        manager.add_prompt(fn)
         messages = await manager.render_prompt("fn", arguments={"name": "World"})
         assert messages == [
             UserMessage(content=TextContent(type="text", text="Hello, World!"))
@@ -106,7 +100,6 @@ def fn(name: str) -> str:
             return f"Hello, {name}!"
 
         manager = PromptManager()
-        prompt = Prompt.from_function(fn)
-        manager.add_prompt(prompt)
+        manager.add_prompt(fn)
         with pytest.raises(ValueError, match="Missing required arguments"):
             await manager.render_prompt("fn")