modelcontextprotocol · Kludex · Jul 6, 2025 · Jul 4, 2025 · Jul 4, 2025 · Jul 1, 2025
diff --git a/.github/workflows/shared.yml b/.github/workflows/shared.yml
@@ -26,6 +26,7 @@ jobs:
   test:
     runs-on: ${{ matrix.os }}
     timeout-minutes: 10
+    continue-on-error: true
     strategy:
       matrix:
         python-version: ["3.10", "3.11", "3.12", "3.13"]
@@ -45,4 +46,7 @@ jobs:
 
       - name: Run pytest
         run: uv run --frozen --no-sync pytest
-    continue-on-error: true
+
+      # This must run last as it modifies the environment!
+      - name: Run pytest with lowest versions
+        run: uv run --all-extras --resolution lowest-direct --upgrade pytest
diff --git a/examples/clients/simple-auth-client/mcp_simple_auth_client/main.py b/examples/clients/simple-auth-client/mcp_simple_auth_client/main.py
@@ -81,7 +81,7 @@ def do_GET(self):
             <html>
             <body>
                 <h1>Authorization Failed</h1>
-                <p>Error: {query_params['error'][0]}</p>
+                <p>Error: {query_params["error"][0]}</p>
                 <p>You can close this window and return to the terminal.</p>
             </body>
             </html>

diff --git a/examples/fastmcp/memory.py b/examples/fastmcp/memory.py
@@ -16,7 +16,7 @@
 from dataclasses import dataclass
 from datetime import datetime, timezone
 from pathlib import Path
-from typing import Annotated, Self
+from typing import Annotated, Self, TypeVar
 
 import asyncpg
 import numpy as np
@@ -35,6 +35,8 @@
 DEFAULT_LLM_MODEL = "openai:gpt-4o"
 DEFAULT_EMBEDDING_MODEL = "text-embedding-3-small"
 
+T = TypeVar("T")
+
 mcp = FastMCP(
     "memory",
     dependencies=[
@@ -57,7 +59,7 @@ def cosine_similarity(a: list[float], b: list[float]) -> float:
     return np.dot(a_array, b_array) / (np.linalg.norm(a_array) * np.linalg.norm(b_array))
 
 
-async def do_ai[T](
+async def do_ai(
     user_prompt: str,
     system_prompt: str,
     result_type: type[T] | Annotated,

diff --git a/examples/fastmcp/unicode_example.py b/examples/fastmcp/unicode_example.py
@@ -8,7 +8,7 @@
 mcp = FastMCP()
 
 
-@mcp.tool(description="🌟 A tool that uses various Unicode characters in its description: " "á é í ó ú ñ 漢字 🎉")
+@mcp.tool(description="🌟 A tool that uses various Unicode characters in its description: á é í ó ú ñ 漢字 🎉")
 def hello_unicode(name: str = "世界", greeting: str = "¡Hola") -> str:
     """
     A simple tool that demonstrates Unicode handling in:

diff --git a/examples/servers/simple-auth/mcp_simple_auth/simple_auth_provider.py b/examples/servers/simple-auth/mcp_simple_auth/simple_auth_provider.py
@@ -89,7 +89,7 @@ async def authorize(self, client: OAuthClientInformationFull, params: Authorizat
         }
 
         # Build simple login URL that points to login page
-        auth_url = f"{self.auth_callback_url}" f"?state={state}" f"&client_id={client.client_id}"
+        auth_url = f"{self.auth_callback_url}?state={state}&client_id={client.client_id}"
 
         return auth_url
 
@@ -117,7 +117,7 @@ async def get_login_page(self, state: str) -> HTMLResponse:
             <p><strong>Username:</strong> demo_user<br>
             <strong>Password:</strong> demo_password</p>
 
-            <form action="{self.server_url.rstrip('/')}/login/callback" method="post">
+            <form action="{self.server_url.rstrip("/")}/login/callback" method="post">
                 <input type="hidden" name="state" value="{state}">
                 <div class="form-group">
                     <label>Username:</label>

diff --git a/...les/servers/simple-streamablehttp-stateless/mcp_simple_streamablehttp_stateless/server.py b/...les/servers/simple-streamablehttp-stateless/mcp_simple_streamablehttp_stateless/server.py
@@ -51,7 +51,7 @@ async def call_tool(name: str, arguments: dict) -> list[types.ContentBlock]:
         for i in range(count):
             await ctx.session.send_log_message(
                 level="info",
-                data=f"Notification {i+1}/{count} from caller: {caller}",
+                data=f"Notification {i + 1}/{count} from caller: {caller}",
                 logger="notification_stream",
                 related_request_id=ctx.request_id,
             )

diff --git a/examples/servers/simple-streamablehttp/mcp_simple_streamablehttp/server.py b/examples/servers/simple-streamablehttp/mcp_simple_streamablehttp/server.py
@@ -55,7 +55,7 @@ async def call_tool(name: str, arguments: dict) -> list[types.ContentBlock]:
         for i in range(count):
             # Include more detailed message for resumability demonstration
             notification_msg = (
-                f"[{i+1}/{count}] Event from '{caller}' - "
+                f"[{i + 1}/{count}] Event from '{caller}' - "
                 f"Use Last-Event-ID to resume if disconnected"
             )
             await ctx.session.send_log_message(
@@ -69,7 +69,7 @@ async def call_tool(name: str, arguments: dict) -> list[types.ContentBlock]:
                 # - nowhere (if GET request isn't supported)
                 related_request_id=ctx.request_id,
             )
-            logger.debug(f"Sent notification {i+1}/{count} for caller: {caller}")
+            logger.debug(f"Sent notification {i + 1}/{count} for caller: {caller}")
             if i < count - 1:  # Don't wait after the last notification
                 await anyio.sleep(interval)
 

diff --git a/pyproject.toml b/pyproject.toml
@@ -25,7 +25,7 @@ dependencies = [
     "anyio>=4.5",
     "httpx>=0.27",
     "httpx-sse>=0.4",
-    "pydantic>=2.7.2,<3.0.0",
+    "pydantic>=2.8.0,<3.0.0",
     "starlette>=0.27",
     "python-multipart>=0.0.9",
     "sse-starlette>=1.6.1",
@@ -36,14 +36,13 @@ dependencies = [
 
 [project.optional-dependencies]
 rich = ["rich>=13.9.4"]
-cli = ["typer>=0.12.4", "python-dotenv>=1.0.0"]
+cli = ["typer>=0.16.0", "python-dotenv>=1.0.0"]
 ws = ["websockets>=15.0.1"]
 
 [project.scripts]
 mcp = "mcp.cli:app [cli]"
 
 [tool.uv]
-resolution = "lowest-direct"
 default-groups = ["dev", "docs"]
 required-version = ">=0.7.2"
 
@@ -58,6 +57,7 @@ dev = [
     "pytest-examples>=0.0.14",
     "pytest-pretty>=1.2.0",
     "inline-snapshot>=0.23.0",
+    "dirty-equals>=0.9.0",
 ]
 docs = [
     "mkdocs>=1.6.1",
@@ -123,5 +123,5 @@ filterwarnings = [
     # This should be fixed on Uvicorn's side.
     "ignore::DeprecationWarning:websockets",
     "ignore:websockets.server.WebSocketServerProtocol is deprecated:DeprecationWarning",
-    "ignore:Returning str or bytes.*:DeprecationWarning:mcp.server.lowlevel"
+    "ignore:Returning str or bytes.*:DeprecationWarning:mcp.server.lowlevel",
 ]
diff --git a/src/mcp/cli/claude.py b/src/mcp/cli/claude.py
@@ -35,7 +35,7 @@ def get_uv_path() -> str:
     uv_path = shutil.which("uv")
     if not uv_path:
         logger.error(
-            "uv executable not found in PATH, falling back to 'uv'. " "Please ensure uv is installed and in your PATH"
+            "uv executable not found in PATH, falling back to 'uv'. Please ensure uv is installed and in your PATH"
         )
         return "uv"  # Fall back to just "uv" if not found
     return uv_path

diff --git a/src/mcp/cli/cli.py b/src/mcp/cli/cli.py
@@ -150,10 +150,10 @@ def _check_server_object(server_object: Any, object_name: str):
             True if it's supported.
         """
         if not isinstance(server_object, FastMCP):
-            logger.error(f"The server object {object_name} is of type " f"{type(server_object)} (expecting {FastMCP}).")
+            logger.error(f"The server object {object_name} is of type {type(server_object)} (expecting {FastMCP}).")
             if isinstance(server_object, LowLevelServer):
                 logger.warning(
-                    "Note that only FastMCP server is supported. Low level " "Server class is not yet supported."
+                    "Note that only FastMCP server is supported. Low level Server class is not yet supported."
                 )
             return False
         return True
@@ -164,7 +164,7 @@ def _check_server_object(server_object: Any, object_name: str):
         for name in ["mcp", "server", "app"]:
             if hasattr(module, name):
                 if not _check_server_object(getattr(module, name), f"{file}:{name}"):
-                    logger.error(f"Ignoring object '{file}:{name}' as it's not a valid " "server object")
+                    logger.error(f"Ignoring object '{file}:{name}' as it's not a valid server object")
                     continue
                 return getattr(module, name)
 
@@ -269,7 +269,7 @@ def dev(
         npx_cmd = _get_npx_command()
         if not npx_cmd:
             logger.error(
-                "npx not found. Please ensure Node.js and npm are properly installed " "and added to your system PATH."
+                "npx not found. Please ensure Node.js and npm are properly installed and added to your system PATH."
             )
             sys.exit(1)
 
@@ -371,7 +371,7 @@ def install(
         typer.Option(
             "--name",
             "-n",
-            help="Custom name for the server (defaults to server's name attribute or" " file name)",
+            help="Custom name for the server (defaults to server's name attribute or file name)",
         ),
     ] = None,
     with_editable: Annotated[
@@ -445,7 +445,7 @@ def install(
             name = server.name
         except (ImportError, ModuleNotFoundError) as e:
             logger.debug(
-                "Could not import server (likely missing dependencies), using file" " name",
+                "Could not import server (likely missing dependencies), using file name",
                 extra={"error": str(e)},
             )
             name = file.stem

diff --git a/src/mcp/client/session.py b/src/mcp/client/session.py
@@ -168,7 +168,7 @@ async def initialize(self) -> types.InitializeResult:
         )
 
         if result.protocolVersion not in SUPPORTED_PROTOCOL_VERSIONS:
-            raise RuntimeError("Unsupported protocol version from the server: " f"{result.protocolVersion}")
+            raise RuntimeError(f"Unsupported protocol version from the server: {result.protocolVersion}")
 
         await self.send_notification(
             types.ClientNotification(types.InitializedNotification(method="notifications/initialized"))

diff --git a/src/mcp/client/sse.py b/src/mcp/client/sse.py
@@ -83,7 +83,7 @@ async def sse_reader(
                                             or url_parsed.scheme != endpoint_parsed.scheme
                                         ):
                                             error_msg = (
-                                                "Endpoint origin does not match " f"connection origin: {endpoint_url}"
+                                                f"Endpoint origin does not match connection origin: {endpoint_url}"
                                             )
                                             logger.error(error_msg)
                                             raise ValueError(error_msg)
@@ -125,7 +125,7 @@ async def post_writer(endpoint_url: str):
                                         ),
                                     )
                                     response.raise_for_status()
-                                    logger.debug("Client message sent successfully: " f"{response.status_code}")
+                                    logger.debug(f"Client message sent successfully: {response.status_code}")
                         except Exception as exc:
                             logger.error(f"Error in post_writer: {exc}")
                         finally:

diff --git a/src/mcp/server/auth/handlers/authorize.py b/src/mcp/server/auth/handlers/authorize.py
@@ -33,7 +33,7 @@ class AuthorizationRequest(BaseModel):
     state: str | None = Field(None, description="Optional state parameter")
     scope: str | None = Field(
         None,
-        description="Optional scope; if specified, should be " "a space-separated list of scope strings",
+        description="Optional scope; if specified, should be a space-separated list of scope strings",
     )
     resource: str | None = Field(
         None,

diff --git a/src/mcp/server/auth/handlers/register.py b/src/mcp/server/auth/handlers/register.py
@@ -72,7 +72,7 @@ async def handle(self, request: Request) -> Response:
             return PydanticJSONResponse(
                 content=RegistrationErrorResponse(
                     error="invalid_client_metadata",
-                    error_description="grant_types must be authorization_code " "and refresh_token",
+                    error_description="grant_types must be authorization_code and refresh_token",
                 ),
                 status_code=400,
             )

diff --git a/src/mcp/server/auth/handlers/token.py b/src/mcp/server/auth/handlers/token.py
@@ -119,9 +119,7 @@ async def handle(self, request: Request):
             return self.response(
                 TokenErrorResponse(
                     error="unsupported_grant_type",
-                    error_description=(
-                        f"Unsupported grant type (supported grant types are " f"{client_info.grant_types})"
-                    ),
+                    error_description=(f"Unsupported grant type (supported grant types are {client_info.grant_types})"),
                 )
             )
 
@@ -166,7 +164,7 @@ async def handle(self, request: Request):
                     return self.response(
                         TokenErrorResponse(
                             error="invalid_request",
-                            error_description=("redirect_uri did not match the one " "used when creating auth code"),
+                            error_description=("redirect_uri did not match the one used when creating auth code"),
                         )
                     )
 
@@ -222,7 +220,7 @@ async def handle(self, request: Request):
                         return self.response(
                             TokenErrorResponse(
                                 error="invalid_scope",
-                                error_description=(f"cannot request scope `{scope}` " "not provided by refresh token"),
+                                error_description=(f"cannot request scope `{scope}` not provided by refresh token"),
                             )
                         )
 

diff --git a/src/mcp/server/fastmcp/server.py b/src/mcp/server/fastmcp/server.py
@@ -390,7 +390,7 @@ async def async_tool(x: int, context: Context) -> str:
         # Check if user passed function directly instead of calling decorator
         if callable(name):
             raise TypeError(
-                "The @tool decorator was used incorrectly. " "Did you forget to call it? Use @tool() instead of @tool"
+                "The @tool decorator was used incorrectly. Did you forget to call it? Use @tool() instead of @tool"
             )
 
         def decorator(fn: AnyFunction) -> AnyFunction:
@@ -497,7 +497,7 @@ def decorator(fn: AnyFunction) -> AnyFunction:
 
                 if uri_params != func_params:
                     raise ValueError(
-                        f"Mismatch between URI parameters {uri_params} " f"and function parameters {func_params}"
+                        f"Mismatch between URI parameters {uri_params} and function parameters {func_params}"
                     )
 
                 # Register as template

diff --git a/src/mcp/server/fastmcp/tools/base.py b/src/mcp/server/fastmcp/tools/base.py
@@ -27,7 +27,7 @@ class Tool(BaseModel):
     description: str = Field(description="Description of what the tool does")
     parameters: dict[str, Any] = Field(description="JSON schema for tool parameters")
     fn_metadata: FuncMetadata = Field(
-        description="Metadata about the function including a pydantic model for tool" " arguments"
+        description="Metadata about the function including a pydantic model for tool arguments"
     )
     is_async: bool = Field(description="Whether the tool is async")
     context_kwarg: str | None = Field(None, description="Name of the kwarg that should receive context")

diff --git a/src/mcp/shared/auth.py b/src/mcp/shared/auth.py
@@ -87,7 +87,7 @@ def validate_redirect_uri(self, redirect_uri: AnyUrl | None) -> AnyUrl:
         elif len(self.redirect_uris) == 1:
             return self.redirect_uris[0]
         else:
-            raise InvalidRedirectUriError("redirect_uri must be specified when client " "has multiple registered URIs")
+            raise InvalidRedirectUriError("redirect_uri must be specified when client has multiple registered URIs")
 
 
 class OAuthClientInformationFull(OAuthClientMetadata):

diff --git a/src/mcp/shared/session.py b/src/mcp/shared/session.py
@@ -402,15 +402,15 @@ async def _receive_loop(self) -> None:
                         except Exception as e:
                             # For other validation errors, log and continue
                             logging.warning(
-                                f"Failed to validate notification: {e}. " f"Message was: {message.message.root}"
+                                f"Failed to validate notification: {e}. Message was: {message.message.root}"
                             )
                     else:  # Response or error
                         stream = self._response_streams.pop(message.message.root.id, None)
                         if stream:
                             await stream.send(message.message.root)
                         else:
                             await self._handle_incoming(
-                                RuntimeError("Received response with an unknown " f"request ID: {message}")
+                                RuntimeError(f"Received response with an unknown request ID: {message}")
                             )
 
             except anyio.ClosedResourceError:

diff --git a/tests/client/test_resource_cleanup.py b/tests/client/test_resource_cleanup.py
@@ -57,8 +57,7 @@ async def mock_send(*args, **kwargs):
 
     # Verify that no response streams were leaked
     assert len(session._response_streams) == initial_stream_count, (
-        f"Expected {initial_stream_count} response streams after request, "
-        f"but found {len(session._response_streams)}"
+        f"Expected {initial_stream_count} response streams after request, but found {len(session._response_streams)}"
     )
 
     # Clean up

diff --git a/tests/issues/test_188_concurrency.py b/tests/issues/test_188_concurrency.py
@@ -3,14 +3,15 @@
 from pydantic import AnyUrl
 
 from mcp.server.fastmcp import FastMCP
-from mcp.shared.memory import (
-    create_connected_server_and_client_session as create_session,
-)
+from mcp.shared.memory import create_connected_server_and_client_session as create_session
 
 _sleep_time_seconds = 0.01
 _resource_name = "slow://slow_resource"
 
 
+@pytest.mark.filterwarnings(
+    "ignore:coroutine 'test_messages_are_executed_concurrently.<locals>.slow_resource' was never awaited:RuntimeWarning"
+)
 @pytest.mark.anyio
 async def test_messages_are_executed_concurrently():
     server = FastMCP("test")
@@ -46,15 +47,3 @@ async def slow_resource():
                 active_calls -= 1
         print(f"Max concurrent calls: {max_concurrent_calls}")
         assert max_concurrent_calls > 1, "No concurrent calls were executed"
-
-
-def main():
-    anyio.run(test_messages_are_executed_concurrently)
-
-
-if __name__ == "__main__":
-    import logging
-
-    logging.basicConfig(level=logging.DEBUG)
-
-    main()
diff --git a/tests/server/fastmcp/auth/test_auth_integration.py b/tests/server/fastmcp/auth/test_auth_integration.py
@@ -658,7 +658,7 @@ async def test_client_registration_invalid_uri(self, test_client: httpx.AsyncCli
         assert "error" in error_data
         assert error_data["error"] == "invalid_client_metadata"
         assert error_data["error_description"] == (
-            "redirect_uris.0: Input should be a valid URL, " "relative URL without a base"
+            "redirect_uris.0: Input should be a valid URL, relative URL without a base"
         )
 
     @pytest.mark.anyio