Merge branch 'main' into main

Author: felixweinberger

README.md

@@ -31,22 +31,32 @@
     - [Prompts](#prompts)
     - [Images](#images)
     - [Context](#context)
+      - [Getting Context in Functions](#getting-context-in-functions)
+      - [Context Properties and Methods](#context-properties-and-methods)
     - [Completions](#completions)
     - [Elicitation](#elicitation)
     - [Sampling](#sampling)
     - [Logging and Notifications](#logging-and-notifications)
     - [Authentication](#authentication)
     - [FastMCP Properties](#fastmcp-properties)
-    - [Session Properties](#session-properties-and-methods)
+    - [Session Properties and Methods](#session-properties-and-methods)
     - [Request Context Properties](#request-context-properties)
   - [Running Your Server](#running-your-server)
     - [Development Mode](#development-mode)
     - [Claude Desktop Integration](#claude-desktop-integration)
     - [Direct Execution](#direct-execution)
     - [Streamable HTTP Transport](#streamable-http-transport)
+      - [CORS Configuration for Browser-Based Clients](#cors-configuration-for-browser-based-clients)
     - [Mounting to an Existing ASGI Server](#mounting-to-an-existing-asgi-server)
+      - [StreamableHTTP servers](#streamablehttp-servers)
+        - [Basic mounting](#basic-mounting)
+        - [Host-based routing](#host-based-routing)
+        - [Multiple servers with path configuration](#multiple-servers-with-path-configuration)
+        - [Path configuration at initialization](#path-configuration-at-initialization)
+      - [SSE servers](#sse-servers)
   - [Advanced Usage](#advanced-usage)
     - [Low-Level Server](#low-level-server)
+      - [Structured Output Support](#structured-output-support)
     - [Writing MCP Clients](#writing-mcp-clients)
     - [Client Display Utilities](#client-display-utilities)
     - [OAuth Authentication for Clients](#oauth-authentication-for-clients)
@@ -400,7 +410,7 @@ def get_weather(city: str) -> WeatherData:
     """Get weather for a city - returns structured data."""
     # Simulated weather data
     return WeatherData(
-        temperature=72.5,
+        temperature=22.5,
         humidity=45.0,
         condition="sunny",
         wind_speed=5.2,
@@ -2137,6 +2147,7 @@ MCP servers declare capabilities during initialization:
 
 ## Documentation
 
+- [API Reference](https://modelcontextprotocol.github.io/python-sdk/api/)
 - [Model Context Protocol documentation](https://modelcontextprotocol.io)
 - [Model Context Protocol specification](https://spec.modelcontextprotocol.io)
 - [Officially supported servers](https://github.com/modelcontextprotocol/servers)

examples/servers/simple-resource/mcp_simple_resource/server.py

@@ -2,6 +2,7 @@
 import click
 import mcp.types as types
 from mcp.server.lowlevel import Server
+from mcp.server.lowlevel.helper_types import ReadResourceContents
 from pydantic import AnyUrl, FileUrl
 from starlette.requests import Request
 
@@ -46,15 +47,15 @@ async def list_resources() -> list[types.Resource]:
         ]
 
     @app.read_resource()
-    async def read_resource(uri: AnyUrl) -> str | bytes:
+    async def read_resource(uri: AnyUrl):
         if uri.path is None:
             raise ValueError(f"Invalid resource path: {uri}")
         name = uri.path.replace(".txt", "").lstrip("/")
 
         if name not in SAMPLE_RESOURCES:
             raise ValueError(f"Unknown resource: {uri}")
 
-        return SAMPLE_RESOURCES[name]["content"]
+        return [ReadResourceContents(content=SAMPLE_RESOURCES[name]["content"], mime_type="text/plain")]
 
     if transport == "sse":
         from mcp.server.sse import SseServerTransport

examples/snippets/servers/structured_output.py

@@ -24,7 +24,7 @@ def get_weather(city: str) -> WeatherData:
     """Get weather for a city - returns structured data."""
     # Simulated weather data
     return WeatherData(
-        temperature=72.5,
+        temperature=22.5,
         humidity=45.0,
         condition="sunny",
         wind_speed=5.2,

pyproject.toml

@@ -102,18 +102,36 @@ executionEnvironments = [
   { root = "examples/servers", reportUnusedFunction = false },
 ]
 
-[tool.ruff.lint]
-select = ["C4", "E", "F", "I", "PERF", "UP"]
-ignore = ["PERF203"]
-
 [tool.ruff]
 line-length = 120
 target-version = "py310"
 extend-exclude = ["README.md"]
 
+[tool.ruff.lint]
+select = [
+    "C4",    # flake8-comprehensions
+    "C90",   # mccabe
+    "E",     # pycodestyle
+    "F",     # pyflakes
+    "I",     # isort
+    "PERF",  # Perflint
+    "PL",    # Pylint
+    "UP",    # pyupgrade
+]
+ignore = ["PERF203", "PLC0415", "PLR0402"]
+mccabe.max-complexity = 24  # Default is 10
+
 [tool.ruff.lint.per-file-ignores]
 "__init__.py" = ["F401"]
 "tests/server/fastmcp/test_func_metadata.py" = ["E501"]
+"tests/shared/test_progress_notifications.py" = ["PLW0603"]
+
+[tool.ruff.lint.pylint]
+allow-magic-value-types = ["bytes", "float", "int", "str"]
+max-args = 23         # Default is 5
+max-branches = 23     # Default is 12
+max-returns = 13      # Default is 6
+max-statements = 102  # Default is 50
 
 [tool.uv.workspace]
 members = ["examples/servers/*", "examples/snippets"]

src/mcp/client/auth.py

@@ -546,6 +546,6 @@ async def async_auth_flow(self, request: httpx.Request) -> AsyncGenerator[httpx.
                     logger.exception("OAuth flow error")
                     raise
 
-        # Retry with new tokens
-        self._add_auth_header(request)
-        yield request
+                # Retry with new tokens
+                self._add_auth_header(request)
+                yield request

src/mcp/client/session.py

@@ -151,7 +151,6 @@ async def initialize(self) -> types.InitializeResult:
         result = await self.send_request(
             types.ClientRequest(
                 types.InitializeRequest(
-                    method="initialize",
                     params=types.InitializeRequestParams(
                         protocolVersion=types.LATEST_PROTOCOL_VERSION,
                         capabilities=types.ClientCapabilities(
@@ -170,20 +169,14 @@ async def initialize(self) -> types.InitializeResult:
         if result.protocolVersion not in SUPPORTED_PROTOCOL_VERSIONS:
             raise RuntimeError(f"Unsupported protocol version from the server: {result.protocolVersion}")
 
-        await self.send_notification(
-            types.ClientNotification(types.InitializedNotification(method="notifications/initialized"))
-        )
+        await self.send_notification(types.ClientNotification(types.InitializedNotification()))
 
         return result
 
     async def send_ping(self) -> types.EmptyResult:
         """Send a ping request."""
         return await self.send_request(
-            types.ClientRequest(
-                types.PingRequest(
-                    method="ping",
-                )
-            ),
+            types.ClientRequest(types.PingRequest()),
             types.EmptyResult,
         )
 
@@ -198,7 +191,6 @@ async def send_progress_notification(
         await self.send_notification(
             types.ClientNotification(
                 types.ProgressNotification(
-                    method="notifications/progress",
                     params=types.ProgressNotificationParams(
                         progressToken=progress_token,
                         progress=progress,
@@ -214,7 +206,6 @@ async def set_logging_level(self, level: types.LoggingLevel) -> types.EmptyResul
         return await self.send_request(
             types.ClientRequest(
                 types.SetLevelRequest(
-                    method="logging/setLevel",
                     params=types.SetLevelRequestParams(level=level),
                 )
             ),
@@ -226,7 +217,6 @@ async def list_resources(self, cursor: str | None = None) -> types.ListResources
         return await self.send_request(
             types.ClientRequest(
                 types.ListResourcesRequest(
-                    method="resources/list",
                     params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                 )
             ),
@@ -238,7 +228,6 @@ async def list_resource_templates(self, cursor: str | None = None) -> types.List
         return await self.send_request(
             types.ClientRequest(
                 types.ListResourceTemplatesRequest(
-                    method="resources/templates/list",
                     params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                 )
             ),
@@ -250,7 +239,6 @@ async def read_resource(self, uri: AnyUrl) -> types.ReadResourceResult:
         return await self.send_request(
             types.ClientRequest(
                 types.ReadResourceRequest(
-                    method="resources/read",
                     params=types.ReadResourceRequestParams(uri=uri),
                 )
             ),
@@ -262,7 +250,6 @@ async def subscribe_resource(self, uri: AnyUrl) -> types.EmptyResult:
         return await self.send_request(
             types.ClientRequest(
                 types.SubscribeRequest(
-                    method="resources/subscribe",
                     params=types.SubscribeRequestParams(uri=uri),
                 )
             ),
@@ -274,7 +261,6 @@ async def unsubscribe_resource(self, uri: AnyUrl) -> types.EmptyResult:
         return await self.send_request(
             types.ClientRequest(
                 types.UnsubscribeRequest(
-                    method="resources/unsubscribe",
                     params=types.UnsubscribeRequestParams(uri=uri),
                 )
             ),
@@ -293,7 +279,6 @@ async def call_tool(
         result = await self.send_request(
             types.ClientRequest(
                 types.CallToolRequest(
-                    method="tools/call",
                     params=types.CallToolRequestParams(
                         name=name,
                         arguments=arguments,
@@ -337,7 +322,6 @@ async def list_prompts(self, cursor: str | None = None) -> types.ListPromptsResu
         return await self.send_request(
             types.ClientRequest(
                 types.ListPromptsRequest(
-                    method="prompts/list",
                     params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                 )
             ),
@@ -349,7 +333,6 @@ async def get_prompt(self, name: str, arguments: dict[str, str] | None = None) -
         return await self.send_request(
             types.ClientRequest(
                 types.GetPromptRequest(
-                    method="prompts/get",
                     params=types.GetPromptRequestParams(name=name, arguments=arguments),
                 )
             ),
@@ -370,7 +353,6 @@ async def complete(
         return await self.send_request(
             types.ClientRequest(
                 types.CompleteRequest(
-                    method="completion/complete",
                     params=types.CompleteRequestParams(
                         ref=ref,
                         argument=types.CompletionArgument(**argument),
@@ -386,7 +368,6 @@ async def list_tools(self, cursor: str | None = None) -> types.ListToolsResult:
         result = await self.send_request(
             types.ClientRequest(
                 types.ListToolsRequest(
-                    method="tools/list",
                     params=types.PaginatedRequestParams(cursor=cursor) if cursor is not None else None,
                 )
             ),
@@ -402,13 +383,7 @@ async def list_tools(self, cursor: str | None = None) -> types.ListToolsResult:
 
     async def send_roots_list_changed(self) -> None:
         """Send a roots/list_changed notification."""
-        await self.send_notification(
-            types.ClientNotification(
-                types.RootsListChangedNotification(
-                    method="notifications/roots/list_changed",
-                )
-            )
-        )
+        await self.send_notification(types.ClientNotification(types.RootsListChangedNotification()))
 
     async def _received_request(self, responder: RequestResponder[types.ServerRequest, types.ClientResult]) -> None:
         ctx = RequestContext[ClientSession, Any](

src/mcp/client/stdio/__init__.py

@@ -32,6 +32,7 @@
         "HOMEPATH",
         "LOCALAPPDATA",
         "PATH",
+        "PATHEXT",
         "PROCESSOR_ARCHITECTURE",
         "SYSTEMDRIVE",
         "SYSTEMROOT",

src/mcp/client/streamable_http.py

@@ -279,17 +279,19 @@ async def _handle_post_request(self, ctx: RequestContext) -> None:
             if is_initialization:
                 self._maybe_extract_session_id_from_response(response)
 
-            content_type = response.headers.get(CONTENT_TYPE, "").lower()
-
-            if content_type.startswith(JSON):
-                await self._handle_json_response(response, ctx.read_stream_writer, is_initialization)
-            elif content_type.startswith(SSE):
-                await self._handle_sse_response(response, ctx, is_initialization)
-            else:
-                await self._handle_unexpected_content_type(
-                    content_type,
-                    ctx.read_stream_writer,
-                )
+            # Per https://modelcontextprotocol.io/specification/2025-06-18/basic#notifications:
+            # The server MUST NOT send a response to notifications.
+            if isinstance(message.root, JSONRPCRequest):
+                content_type = response.headers.get(CONTENT_TYPE, "").lower()
+                if content_type.startswith(JSON):
+                    await self._handle_json_response(response, ctx.read_stream_writer, is_initialization)
+                elif content_type.startswith(SSE):
+                    await self._handle_sse_response(response, ctx, is_initialization)
+                else:
+                    await self._handle_unexpected_content_type(
+                        content_type,
+                        ctx.read_stream_writer,
+                    )
 
     async def _handle_json_response(
         self,

src/mcp/server/auth/provider.py

@@ -281,7 +281,7 @@ async def revoke_token(
 
 def construct_redirect_uri(redirect_uri_base: str, **params: str | None) -> str:
     parsed_uri = urlparse(redirect_uri_base)
-    query_params = [(k, v) for k, vs in parse_qs(parsed_uri.query) for v in vs]
+    query_params = [(k, v) for k, vs in parse_qs(parsed_uri.query).items() for v in vs]
     for k, v in params.items():
         if v is not None:
             query_params.append((k, v))

src/mcp/server/fastmcp/__init__.py

@@ -3,7 +3,7 @@
 from importlib.metadata import version
 
 from .server import Context, FastMCP
-from .utilities.types import Image
+from .utilities.types import Audio, Image
 
 __version__ = version("mcp")
-__all__ = ["FastMCP", "Context", "Image"]
+__all__ = ["FastMCP", "Context", "Image", "Audio"]