Updating initialization and Implementation to match specs update (add title and description)

Author: yannj-fr

src/mcp/server/fastmcp/server.py

@@ -143,6 +143,8 @@ class FastMCP(Generic[LifespanResultT]):
     def __init__(  # noqa: PLR0913
         self,
         name: str | None = None,
+        title: str | None = None,
+        description: str | None = None,
         instructions: str | None = None,
         website_url: str | None = None,
         icons: list[Icon] | None = None,
@@ -192,6 +194,8 @@ def __init__(  # noqa: PLR0913
 
         self._mcp_server = MCPServer(
             name=name or "FastMCP",
+            title=title,
+            description=description,
             instructions=instructions,
             website_url=website_url,
             icons=icons,
@@ -233,6 +237,14 @@ def __init__(  # noqa: PLR0913
     def name(self) -> str:
         return self._mcp_server.name
 
+    @property
+    def title(self) -> str | None:
+        return self._mcp_server.title
+
+    @property
+    def description(self) -> str | None:
+        return self._mcp_server.description
+
     @property
     def instructions(self) -> str | None:
         return self._mcp_server.instructions

src/mcp/server/lowlevel/server.py

@@ -135,6 +135,8 @@ def __init__(
         self,
         name: str,
         version: str | None = None,
+        title: str | None = None,
+        description: str | None = None,
         instructions: str | None = None,
         website_url: str | None = None,
         icons: list[types.Icon] | None = None,
@@ -145,6 +147,8 @@ def __init__(
     ):
         self.name = name
         self.version = version
+        self.title = title
+        self.description = description
         self.instructions = instructions
         self.website_url = website_url
         self.icons = icons
@@ -176,6 +180,8 @@ def pkg_version(package: str) -> str:
         return InitializationOptions(
             server_name=self.name,
             server_version=self.version if self.version else pkg_version("mcp"),
+            title=self.title,
+            description=self.description,
             capabilities=self.get_capabilities(
                 notification_options or NotificationOptions(),
                 experimental_capabilities or {},

src/mcp/server/models.py

@@ -14,6 +14,8 @@
 class InitializationOptions(BaseModel):
     server_name: str
     server_version: str
+    title: str | None = None
+    description: str | None = None
     capabilities: ServerCapabilities
     instructions: str | None = None
     website_url: str | None = None

src/mcp/server/session.py

@@ -155,6 +155,8 @@ async def _received_request(self, responder: RequestResponder[types.ClientReques
                                 capabilities=self._init_options.capabilities,
                                 serverInfo=types.Implementation(
                                     name=self._init_options.server_name,
+                                    title=self._init_options.title,
+                                    description=self._init_options.description,
                                     version=self._init_options.server_version,
                                     websiteUrl=self._init_options.website_url,
                                     icons=self._init_options.icons,

src/mcp/types.py

@@ -233,6 +233,12 @@ class Implementation(BaseMetadata):
 
     version: str
 
+    title: str | None = None
+    """An optional human-readable title for this implementation."""
+
+    description: str | None = None
+    """An optional human-readable description of what this implementation does."""
+
     websiteUrl: str | None = None
     """An optional URL of the website for this implementation."""
 

tests/server/fastmcp/test_server.py

@@ -35,12 +35,16 @@ class TestServer:
     @pytest.mark.anyio
     async def test_create_server(self):
         mcp = FastMCP(
+            title="FastMCP Server",
+            description="Server description",
             instructions="Server instructions",
             website_url="https://example.com/mcp_server",
             version="1.0",
             icons=[Icon(src="https://example.com/icon.png", mimeType="image/png", sizes=["48x48", "96x96"])],
         )
         assert mcp.name == "FastMCP"
+        assert mcp.title == "FastMCP Server"
+        assert mcp.description == "Server description"
         assert mcp.instructions == "Server instructions"
         assert mcp.website_url == "https://example.com/mcp_server"
         assert mcp.version == "1.0"

tests/server/fastmcp/test_title.py

@@ -10,6 +10,29 @@
 from mcp.types import Prompt, Resource, ResourceTemplate, Tool, ToolAnnotations
 
 
+@pytest.mark.anyio
+async def test_server_name_title_description_version():
+    """Test that server title and description are set and retrievable correctly."""
+    mcp = FastMCP(
+        name="TestServer",
+        title="Test Server Title",
+        description="This is a test server description.",
+        version="1.0",
+    )
+
+    assert mcp.title == "Test Server Title"
+    assert mcp.description == "This is a test server description."
+    assert mcp.version == "1.0"
+
+    # Start server and connect client
+    async with create_connected_server_and_client_session(mcp._mcp_server) as client:
+        init_result = await client.initialize()
+        assert init_result.serverInfo.name == "TestServer"
+        assert init_result.serverInfo.title == "Test Server Title"
+        assert init_result.serverInfo.description == "This is a test server description."
+        assert init_result.serverInfo.version == "1.0"
+
+
 @pytest.mark.anyio
 async def test_tool_title_precedence():
     """Test that tool title precedence works correctly: title > annotations.title > name."""