Merge branch 'main' into basil/resource_streams

Author: bhosmer-ant

examples/clients/simple-chatbot/mcp_simple_chatbot/main.py

@@ -122,8 +122,10 @@ async def list_tools(self) -> list[Any]:
 
         for item in tools_response:
             if isinstance(item, tuple) and item[0] == "tools":
-                for tool in item[1]:
-                    tools.append(Tool(tool.name, tool.description, tool.inputSchema))
+                tools.extend(
+                    Tool(tool.name, tool.description, tool.inputSchema)
+                    for tool in item[1]
+                )
 
         return tools
 
@@ -282,10 +284,9 @@ def __init__(self, servers: list[Server], llm_client: LLMClient) -> None:
 
     async def cleanup_servers(self) -> None:
         """Clean up all servers properly."""
-        cleanup_tasks = []
-        for server in self.servers:
-            cleanup_tasks.append(asyncio.create_task(server.cleanup()))
-
+        cleanup_tasks = [
+            asyncio.create_task(server.cleanup()) for server in self.servers
+        ]
         if cleanup_tasks:
             try:
                 await asyncio.gather(*cleanup_tasks, return_exceptions=True)

pyproject.toml

@@ -29,7 +29,7 @@ dependencies = [
     "starlette>=0.27",
     "sse-starlette>=1.6.1",
     "pydantic-settings>=2.5.2",
-    "uvicorn>=0.23.1",
+    "uvicorn>=0.23.1; sys_platform != 'emscripten'",
 ]
 
 [project.optional-dependencies]
@@ -89,8 +89,8 @@ venv = ".venv"
 strict = ["src/mcp/**/*.py"]
 
 [tool.ruff.lint]
-select = ["E", "F", "I", "UP"]
-ignore = []
+select = ["C4", "E", "F", "I", "PERF", "UP"]
+ignore = ["PERF203"]
 
 [tool.ruff]
 line-length = 88

src/mcp/client/session.py

@@ -254,7 +254,10 @@ async def unsubscribe_resource(self, uri: AnyUrl) -> types.EmptyResult:
         )
 
     async def call_tool(
-        self, name: str, arguments: dict[str, Any] | None = None
+        self,
+        name: str,
+        arguments: dict[str, Any] | None = None,
+        read_timeout_seconds: timedelta | None = None,
     ) -> types.CallToolResult:
         """Send a tools/call request."""
         return await self.send_request(
@@ -265,6 +268,7 @@ async def call_tool(
                 )
             ),
             types.CallToolResult,
+            request_read_timeout_seconds=read_timeout_seconds,
         )
 
     async def list_prompts(self) -> types.ListPromptsResult:

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

@@ -1,7 +1,6 @@
 """Base classes for FastMCP prompts."""
 
 import inspect
-import json
 from collections.abc import Awaitable, Callable, Sequence
 from typing import Any, Literal
 
@@ -155,7 +154,9 @@ async def render(self, arguments: dict[str, Any] | None = None) -> list[Message]
                         content = TextContent(type="text", text=msg)
                         messages.append(UserMessage(content=content))
                     else:
-                        content = json.dumps(pydantic_core.to_jsonable_python(msg))
+                        content = pydantic_core.to_json(
+                            msg, fallback=str, indent=2
+                        ).decode()
                         messages.append(Message(role="user", content=content))
                 except Exception:
                     raise ValueError(

src/mcp/server/fastmcp/resources/types.py

@@ -9,7 +9,7 @@
 import anyio
 import anyio.to_thread
 import httpx
-import pydantic.json
+import pydantic
 import pydantic_core
 from pydantic import Field, ValidationInfo
 
@@ -59,15 +59,12 @@ async def read(self) -> str | bytes:
             )
             if isinstance(result, Resource):
                 return await result.read()
-            if isinstance(result, bytes):
+            elif isinstance(result, bytes):
                 return result
-            if isinstance(result, str):
+            elif isinstance(result, str):
                 return result
-            try:
-                return json.dumps(pydantic_core.to_jsonable_python(result))
-            except (TypeError, pydantic_core.PydanticSerializationError):
-                # If JSON serialization fails, try str()
-                return str(result)
+            else:
+                return pydantic_core.to_json(result, fallback=str, indent=2).decode()
         except Exception as e:
             raise ValueError(f"Error reading resource {self.uri}: {e}")
 

src/mcp/server/fastmcp/server.py

@@ -3,7 +3,6 @@
 from __future__ import annotations as _annotations
 
 import inspect
-import json
 import re
 from collections.abc import AsyncIterator, Callable, Iterable, Sequence
 from contextlib import (
@@ -15,7 +14,6 @@
 
 import anyio
 import pydantic_core
-import uvicorn
 from pydantic import BaseModel, Field
 from pydantic.networks import AnyUrl
 from pydantic_settings import BaseSettings, SettingsConfigDict
@@ -466,6 +464,8 @@ async def run_stdio_async(self) -> None:
 
     async def run_sse_async(self) -> None:
         """Run the server using SSE transport."""
+        import uvicorn
+
         starlette_app = self.sse_app()
 
         config = uvicorn.Config(
@@ -550,10 +550,7 @@ def _convert_to_content(
         return list(chain.from_iterable(_convert_to_content(item) for item in result))  # type: ignore[reportUnknownVariableType]
 
     if not isinstance(result, str):
-        try:
-            result = json.dumps(pydantic_core.to_jsonable_python(result))
-        except Exception:
-            result = str(result)
+        result = pydantic_core.to_json(result, fallback=str, indent=2).decode()
 
     return [TextContent(type="text", text=result)]
 

src/mcp/server/fastmcp/utilities/func_metadata.py

@@ -80,7 +80,7 @@ def pre_parse_json(self, data: dict[str, Any]) -> dict[str, Any]:
         dicts (JSON objects) as JSON strings, which can be pre-parsed here.
         """
         new_data = data.copy()  # Shallow copy
-        for field_name, _field_info in self.arg_model.model_fields.items():
+        for field_name in self.arg_model.model_fields.keys():
             if field_name not in data.keys():
                 continue
             if isinstance(data[field_name], str):

src/mcp/shared/session.py

@@ -185,7 +185,7 @@ def __init__(
         self._request_id = 0
         self._receive_request_type = receive_request_type
         self._receive_notification_type = receive_notification_type
-        self._read_timeout_seconds = read_timeout_seconds
+        self._session_read_timeout_seconds = read_timeout_seconds
         self._in_flight = {}
         self._exit_stack = AsyncExitStack()
 
@@ -212,10 +212,12 @@ async def send_request(
         self,
         request: SendRequestT,
         result_type: type[ReceiveResultT],
+        request_read_timeout_seconds: timedelta | None = None,
     ) -> ReceiveResultT:
         """
         Sends a request and wait for a response. Raises an McpError if the
-        response contains an error.
+        response contains an error. If a request read timeout is provided, it
+        will take precedence over the session read timeout.
 
         Do not use this method to emit notifications! Use send_notification()
         instead.
@@ -240,12 +242,15 @@ async def send_request(
 
             await self._write_stream.send(JSONRPCMessage(jsonrpc_request))
 
+            # request read timeout takes precedence over session read timeout
+            timeout = None
+            if request_read_timeout_seconds is not None:
+                timeout = request_read_timeout_seconds.total_seconds()
+            elif self._session_read_timeout_seconds is not None:
+                timeout = self._session_read_timeout_seconds.total_seconds()
+
             try:
-                with anyio.fail_after(
-                    None
-                    if self._read_timeout_seconds is None
-                    else self._read_timeout_seconds.total_seconds()
-                ):
+                with anyio.fail_after(timeout):
                     response_or_error = await response_stream_reader.receive()
             except TimeoutError:
                 raise McpError(
@@ -254,7 +259,7 @@ async def send_request(
                         message=(
                             f"Timed out while waiting for response to "
                             f"{request.__class__.__name__}. Waited "
-                            f"{self._read_timeout_seconds} seconds."
+                            f"{timeout} seconds."
                         ),
                     )
                 )

tests/issues/test_342_base64_encoding.py

@@ -42,7 +42,7 @@ async def test_server_base64_encoding_issue():
 
     # Create binary data that will definitely result in + and / characters
     # when encoded with standard base64
-    binary_data = bytes([x for x in range(255)] * 4)
+    binary_data = bytes(list(range(255)) * 4)
 
     # Register a resource handler that returns our test data
     @server.read_resource()

tests/server/fastmcp/prompts/test_base.py

@@ -38,7 +38,7 @@ async def fn(name: str, age: int = 30) -> str:
             return f"Hello, {name}! You're {age} years old."
 
         prompt = Prompt.from_function(fn)
-        assert await prompt.render(arguments=dict(name="World")) == [
+        assert await prompt.render(arguments={"name": "World"}) == [
             UserMessage(
                 content=TextContent(
                     type="text", text="Hello, World! You're 30 years old."
@@ -53,7 +53,7 @@ async def fn(name: str, age: int = 30) -> str:
 
         prompt = Prompt.from_function(fn)
         with pytest.raises(ValueError):
-            await prompt.render(arguments=dict(age=40))
+            await prompt.render(arguments={"age": 40})
 
     @pytest.mark.anyio
     async def test_fn_returns_message(self):