fix(langchain): widen langchain.mcp client type to Client[Any]

`load_mcp_tools`, `convert_mcp_tool`, and `call_tool_with_elicitation` annotated
their FastMCP client as `Client[ClientTransport]`. FastMCP's `Client` is invariant
in its transport type parameter, so no concrete client a caller constructs (e.g.
`Client(url)`, which infers a transport union) satisfies `Client[ClientTransport]` —
every real caller hits a mypy arg-type error. Widen the annotation to `Client[Any]`
and drop the now-unused `ClientTransport` import. Pure static-typing change; runtime
behavior is unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

libs/langchain_v1/langchain/mcp/_elicitation.py

@@ -23,7 +23,6 @@ from typing_extensions import NotRequired, TypedDict
 
 if TYPE_CHECKING:
     from fastmcp import Client
-    from fastmcp.client.transports import ClientTransport
     from mcp.types import CallToolResult, InputResponses
 
 _VALID_ACTIONS = ("accept", "decline", "cancel")
@@ -45,7 +44,7 @@ class MCPElicitation(TypedDict):
 
 
 async def call_tool_with_elicitation(
-    client: Client[ClientTransport],
+    client: Client[Any],
     name: str,
     arguments: dict[str, Any],
 ) -> CallToolResult:

libs/langchain_v1/langchain/mcp/tools.py

@@ -26,7 +26,6 @@ if TYPE_CHECKING:
     from collections.abc import Sequence
 
     from fastmcp import Client
-    from fastmcp.client.transports import ClientTransport
     from langchain_core.tools import BaseTool
     from mcp.types import ContentBlock as MCPContentBlock
     from mcp.types import Tool as MCPTool
@@ -51,7 +50,7 @@ class _ToolResult(Protocol):
 
 
 async def load_mcp_tools(
-    client: Client[ClientTransport],
+    client: Client[Any],
     *,
     elicitation: ElicitationMode | None = None,
 ) -> list[BaseTool]:
@@ -79,7 +78,7 @@ async def load_mcp_tools(
 
 def convert_mcp_tool(
     tool: MCPTool,
-    client: Client[ClientTransport],
+    client: Client[Any],
     *,
     elicitation: ElicitationMode | None = None,
 ) -> BaseTool: