New type filecontent

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

@@ -7,9 +7,9 @@
 import pydantic_core
 from pydantic import BaseModel, Field, TypeAdapter, validate_call
 
-from mcp.types import EmbeddedResource, ImageContent, TextContent
+from mcp.types import EmbeddedResource, ImageContent, TextContent, FileContent
 
-CONTENT_TYPES = TextContent | ImageContent | EmbeddedResource
+CONTENT_TYPES = TextContent | ImageContent | EmbeddedResource | FileContent
 
 
 class Message(BaseModel):

src/mcp/server/fastmcp/server.py

@@ -57,6 +57,7 @@
     ImageContent,
     TextContent,
     ToolAnnotations,
+    FileContent,
 )
 from mcp.types import Prompt as MCPPrompt
 from mcp.types import PromptArgument as MCPPromptArgument
@@ -273,7 +274,7 @@ def get_context(self) -> Context[ServerSession, object]:
 
     async def call_tool(
         self, name: str, arguments: dict[str, Any]
-    ) -> Sequence[TextContent | ImageContent | EmbeddedResource]:
+    ) -> Sequence[TextContent | ImageContent | EmbeddedResource | FileContent]:
         """Call a tool by name with arguments."""
         context = self.get_context()
         result = await self._tool_manager.call_tool(name, arguments, context=context)
@@ -873,12 +874,12 @@ async def get_prompt(
 
 def _convert_to_content(
     result: Any,
-) -> Sequence[TextContent | ImageContent | EmbeddedResource]:
+) -> Sequence[TextContent | ImageContent | EmbeddedResource | FileContent]:
     """Convert a result to a sequence of content objects."""
     if result is None:
         return []
 
-    if isinstance(result, TextContent | ImageContent | EmbeddedResource):
+    if isinstance(result, TextContent | ImageContent | EmbeddedResource | FileContent):
         return [result]
 
     if isinstance(result, Image):

src/mcp/server/lowlevel/server.py

@@ -400,7 +400,10 @@ def decorator(
                 ...,
                 Awaitable[
                     Iterable[
-                        types.TextContent | types.ImageContent | types.EmbeddedResource
+                        types.TextContent
+                        | types.ImageContent
+                        | types.EmbeddedResource
+                        | types.FileContent
                     ]
                 ],
             ],

src/mcp/types.py

@@ -653,6 +653,21 @@ class ImageContent(BaseModel):
     model_config = ConfigDict(extra="allow")
 
 
+class FileContent(BaseModel):
+    """File content for a message."""
+
+    type: Literal["file"]
+    filename: str
+    data: str
+    """The base64-encoded file data."""
+    mimeType: str
+    """
+    The file mimetype 
+    """
+    annotations: Annotations | None = None
+    model_config = ConfigDict(extra="allow")
+
+
 class SamplingMessage(BaseModel):
     """Describes a message issued to or received from an LLM API."""
 
@@ -797,7 +812,7 @@ class CallToolRequest(Request[CallToolRequestParams, Literal["tools/call"]]):
 class CallToolResult(Result):
     """The server's response to a tool call."""
 
-    content: list[TextContent | ImageContent | EmbeddedResource]
+    content: list[TextContent | ImageContent | EmbeddedResource | FileContent]
     isError: bool = False
 
 

tests/server/fastmcp/test_server.py

@@ -18,6 +18,7 @@
 from mcp.types import (
     BlobResourceContents,
     ImageContent,
+    FileContent,
     TextContent,
     TextResourceContents,
 )
@@ -59,7 +60,7 @@ async def test_sse_app_with_mount_path(self):
         # Test with default mount path
         mcp = FastMCP()
         with patch.object(
-            mcp, "_normalize_path", return_value="/messages/"
+                mcp, "_normalize_path", return_value="/messages/"
         ) as mock_normalize:
             mcp.sse_app()
             # Verify _normalize_path was called with correct args
@@ -69,7 +70,7 @@ async def test_sse_app_with_mount_path(self):
         mcp = FastMCP()
         mcp.settings.mount_path = "/custom"
         with patch.object(
-            mcp, "_normalize_path", return_value="/custom/messages/"
+                mcp, "_normalize_path", return_value="/custom/messages/"
         ) as mock_normalize:
             mcp.sse_app()
             # Verify _normalize_path was called with correct args
@@ -78,7 +79,7 @@ async def test_sse_app_with_mount_path(self):
         # Test with mount_path parameter
         mcp = FastMCP()
         with patch.object(
-            mcp, "_normalize_path", return_value="/param/messages/"
+                mcp, "_normalize_path", return_value="/param/messages/"
         ) as mock_normalize:
             mcp.sse_app(mount_path="/param")
             # Verify _normalize_path was called with correct args
@@ -103,7 +104,7 @@ async def test_starlette_routes_with_mount_path(self):
         # Verify path values
         assert sse_routes[0].path == "/sse", "SSE route path should be /sse"
         assert (
-            mount_routes[0].path == "/messages"
+                mount_routes[0].path == "/messages"
         ), "Mount route path should be /messages"
 
         # Test with mount path as parameter
@@ -121,7 +122,7 @@ async def test_starlette_routes_with_mount_path(self):
         # Verify path values
         assert sse_routes[0].path == "/sse", "SSE route path should be /sse"
         assert (
-            mount_routes[0].path == "/messages"
+                mount_routes[0].path == "/messages"
         ), "Mount route path should be /messages"
 
     @pytest.mark.anyio
@@ -131,7 +132,7 @@ async def test_non_ascii_description(self):
 
         @mcp.tool(
             description=(
-                "🌟 This tool uses emojis and UTF-8 characters: á é í ó ú ñ 漢字 🎉"
+                    "🌟 This tool uses emojis and UTF-8 characters: á é í ó ú ñ 漢字 🎉"
             )
         )
         def hello_world(name: str = "世界") -> str:
@@ -167,7 +168,6 @@ async def test_add_tool_decorator_incorrect_usage(self):
         mcp = FastMCP()
 
         with pytest.raises(TypeError, match="The @tool decorator was used incorrectly"):
-
             @mcp.tool  # Missing parentheses #type: ignore
             def add(x: int, y: int) -> int:
                 return x + y
@@ -187,9 +187,8 @@ async def test_add_resource_decorator_incorrect_usage(self):
         mcp = FastMCP()
 
         with pytest.raises(
-            TypeError, match="The @resource decorator was used incorrectly"
+                TypeError, match="The @resource decorator was used incorrectly"
         ):
-
             @mcp.resource  # Missing parentheses #type: ignore
             def get_data(x: str) -> str:
                 return f"Data: {x}"
@@ -207,10 +206,11 @@ def image_tool_fn(path: str) -> Image:
     return Image(path)
 
 
-def mixed_content_tool_fn() -> list[TextContent | ImageContent]:
+def mixed_content_tool_fn() -> list[TextContent | ImageContent | FileContent]:
     return [
         TextContent(type="text", text="Hello"),
         ImageContent(type="image", data="abc", mimeType="image/png"),
+        FileContent(type="file", data="abc", filename="test.pdf", mimeType="application/pdf"),
     ]
 
 
@@ -312,14 +312,18 @@ async def test_tool_mixed_content(self):
         mcp.add_tool(mixed_content_tool_fn)
         async with client_session(mcp._mcp_server) as client:
             result = await client.call_tool("mixed_content_tool_fn", {})
-            assert len(result.content) == 2
+            assert len(result.content) == 3
             content1 = result.content[0]
             content2 = result.content[1]
+            content3 = result.content[2]
             assert isinstance(content1, TextContent)
             assert content1.text == "Hello"
             assert isinstance(content2, ImageContent)
             assert content2.mimeType == "image/png"
             assert content2.data == "abc"
+            assert isinstance(content3, FileContent)
+            assert content3.mimeType == "application/pdf"
+            assert content3.data == "abc"
 
     @pytest.mark.anyio
     async def test_tool_mixed_list_with_image(self, tmp_path: Path):
@@ -437,8 +441,8 @@ async def test_file_resource_binary(self, tmp_path: Path):
             result = await client.read_resource(AnyUrl("file://test.bin"))
             assert isinstance(result.contents[0], BlobResourceContents)
             assert (
-                result.contents[0].blob
-                == base64.b64encode(b"Binary file data").decode()
+                    result.contents[0].blob
+                    == base64.b64encode(b"Binary file data").decode()
             )
 
     @pytest.mark.anyio
@@ -468,7 +472,6 @@ async def test_resource_with_params(self):
         mcp = FastMCP()
 
         with pytest.raises(ValueError, match="Mismatch between URI parameters"):
-
             @mcp.resource("resource://data")
             def get_data_fn(param: str) -> str:
                 return f"Data: {param}"
@@ -479,7 +482,6 @@ async def test_resource_with_uri_params(self):
         mcp = FastMCP()
 
         with pytest.raises(ValueError, match="Mismatch between URI parameters"):
-
             @mcp.resource("resource://{param}")
             def get_data() -> str:
                 return "Data"
@@ -513,7 +515,6 @@ async def test_resource_mismatched_params(self):
         mcp = FastMCP()
 
         with pytest.raises(ValueError, match="Mismatch between URI parameters"):
-
             @mcp.resource("resource://{name}/data")
             def get_data(user: str) -> str:
                 return f"Data for {user}"
@@ -540,7 +541,6 @@ async def test_resource_multiple_mismatched_params(self):
         mcp = FastMCP()
 
         with pytest.raises(ValueError, match="Mismatch between URI parameters"):
-
             @mcp.resource("resource://{org}/{repo}/data")
             def get_data_mismatched(org: str, repo_2: str) -> str:
                 return f"Data for {org}"
@@ -774,7 +774,6 @@ def test_prompt_decorator_error(self):
         """Test error when decorator is used incorrectly."""
         mcp = FastMCP()
         with pytest.raises(TypeError, match="decorator was used incorrectly"):
-
             @mcp.prompt  # type: ignore
             def fn() -> str:
                 return "Hello, world!"