address PR comments

Author: ramjibc

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

@@ -26,18 +26,23 @@ def list_prompts(self) -> list[Prompt]:
 
     def add_prompt(
         self,
-        fn: AnyFunction,
+        prompt_or_fn: Prompt | AnyFunction,
         name: str | None = None,
         description: str | None = None,
     ) -> Prompt:
         """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_or_fn: Either a Prompt instance or a function to create a prompt from
+            name: Optional name for the prompt (only used if prompt_or_fn is a function)
+            description: Optional description of the prompt (only used if prompt_or_fn is a function)
         """
-        prompt = Prompt.from_function(fn, name=name, description=description)
+        if isinstance(prompt_or_fn, Prompt):
+            prompt = prompt_or_fn
+        else:
+            prompt = Prompt.from_function(
+                prompt_or_fn, name=name, description=description
+            )
 
         # Check for duplicates
         existing = self._prompts.get(prompt.name)

src/mcp/server/fastmcp/server.py

@@ -36,6 +36,7 @@
 )
 from mcp.server.fastmcp.exceptions import ResourceError
 from mcp.server.fastmcp.prompts import PromptManager
+from mcp.server.fastmcp.prompts.base import Prompt
 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
@@ -486,18 +487,20 @@ def decorator(fn: AnyFunction) -> AnyFunction:
 
     def add_prompt(
         self,
-        fn: AnyFunction,
+        prompt_or_fn: Prompt | AnyFunction,
         name: str | None = None,
         description: str | None = None,
     ) -> None:
         """Add a prompt to the server.
 
         Args:
-            fn: Function to create a prompt from
-            name: Optional name for the prompt
-            description: Optional description of the prompt
+            prompt_or_fn: Either a Prompt instance or a function to create a prompt from
+            name: Optional name for the prompt (only used if prompt_or_fn is a function)
+            description: Optional description of the prompt (only used if prompt_or_fn is a function)
         """
-        self._prompt_manager.add_prompt(fn, name=name, description=description)
+        self._prompt_manager.add_prompt(
+            prompt_or_fn, name=name, description=description
+        )
 
     def prompt(
         self, name: str | None = None, description: str | None = None

tests/server/fastmcp/prompts/test_manager.py

@@ -17,6 +17,35 @@ def fn() -> str:
         assert added.name == "fn"
         assert manager.get_prompt("fn") == added
 
+    def test_add_prompt_object(self):
+        """Test adding a Prompt object directly."""
+
+        def fn() -> str:
+            return "Hello, world!"
+
+        prompt = Prompt.from_function(fn, name="test_prompt", description="Test prompt")
+        manager = PromptManager()
+        added = manager.add_prompt(prompt)
+        assert added == prompt
+        assert manager.get_prompt("test_prompt") == prompt
+
+    def test_add_prompt_object_ignores_name_and_description(self):
+        """Test that name and description args are ignored when adding a Prompt object."""
+
+        def fn() -> str:
+            return "Hello, world!"
+
+        prompt = Prompt.from_function(
+            fn, name="original_name", description="Original description"
+        )
+        manager = PromptManager()
+        # These should be ignored
+        added = manager.add_prompt(
+            prompt, name="ignored_name", description="ignored_description"
+        )
+        assert added.name == "original_name"
+        assert added.description == "Original description"
+
     def test_add_duplicate_prompt(self, caplog):
         """Test adding the same prompt twice."""
 

tests/server/fastmcp/test_server.py

@@ -8,7 +8,12 @@
 from starlette.routing import Mount, Route
 
 from mcp.server.fastmcp import Context, FastMCP
-from mcp.server.fastmcp.prompts.base import EmbeddedResource, Message, UserMessage
+from mcp.server.fastmcp.prompts.base import (
+    EmbeddedResource,
+    Message,
+    UserMessage,
+    Prompt,
+)
 from mcp.server.fastmcp.resources import FileResource, FunctionResource
 from mcp.server.fastmcp.utilities.types import Image
 from mcp.shared.exceptions import McpError
@@ -851,3 +856,50 @@ def prompt_fn(name: str) -> str:
         async with client_session(mcp._mcp_server) as client:
             with pytest.raises(McpError, match="Missing required arguments"):
                 await client.get_prompt("prompt_fn")
+
+    @pytest.mark.anyio
+    async def test_add_prompt_object(self):
+        """Test adding a Prompt object directly to FastMCP server."""
+
+        def fn() -> str:
+            return "Hello from custom prompt!"
+
+        mcp = FastMCP()
+        prompt = Prompt.from_function(
+            fn, name="custom_prompt", description="A custom prompt"
+        )
+        mcp.add_prompt(prompt)
+
+        prompts = mcp._prompt_manager.list_prompts()
+        assert len(prompts) == 1
+        assert prompts[0].name == "custom_prompt"
+        assert prompts[0].description == "A custom prompt"
+
+    @pytest.mark.anyio
+    async def test_add_prompt_object_through_protocol(self):
+        """Test that Prompt objects added directly work through MCP protocol."""
+
+        def fn(name: str) -> str:
+            return f"Hello, {name}!"
+
+        mcp = FastMCP()
+        prompt = Prompt.from_function(
+            fn, name="custom_greeting", description="Custom greeting prompt"
+        )
+        mcp.add_prompt(prompt)
+
+        async with client_session(mcp._mcp_server) as client:
+            # List prompts
+            result = await client.list_prompts()
+            assert len(result.prompts) == 1
+            assert result.prompts[0].name == "custom_greeting"
+            assert result.prompts[0].description == "Custom greeting prompt"
+
+            # Get prompt
+            prompt_result = await client.get_prompt("custom_greeting", {"name": "Test"})
+            assert len(prompt_result.messages) == 1
+            message = prompt_result.messages[0]
+            assert message.role == "user"
+            content = message.content
+            assert isinstance(content, TextContent)
+            assert content.text == "Hello, Test!"