feat: Pass through and expose additional parameters in ClientSessionGroup.call_tool and .connect_to_server

[inaku-Gyan]

Exposed additional optional parameters in the call_tool and connect_to_server methods so that they can fully pass through supported arguments to the underlying session-level methods.

Replace the parameter args in call_tool with arguments so that it's aligned with the original ClientSession.call_tool method.
Use @overload and @deprecated to mark args as deprecated while still supporting its usage.

Motivation and Context

Previously, call_tool and connect_to_server ignored several optional parameters supported by the lower-level ClientSession and session methods.
As a result, certain advanced use cases (e.g., custom timeouts, callbacks, or client metadata) could only be supported by directly accessing lower-level APIs, which was cumbersome and inconsistent.

This change:

• Adds new parameters to call_tool for timeouts, progress tracking, and metadata.
• Adds session_params to connect_to_server to configure ClientSession creation directly.
• Introduces ClientSessionParameters dataclass for clear typing.

How Has This Been Tested?

Pyright static type check and pytest.

Breaking Changes

• Not strictly breaking, as old usage patterns are still supported.
• Minor deprecation warning: The args parameter in call_tool is deprecated in favor of arguments.

Types of changes

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

ClientSessionParameters uses dataclasses.dataclass instead of pydantic.BaseModel because BaseModel does not support Protocol-typed fields. Attempts with SkipValidation and arbitrary_types_allowed=True did not resolve the issue.

[BetterAndBetterII]

we need this :)

[kilvil]

I need this function to refresh tools.

[kylestratis]

Some feedback on the structure of this compared to the rest of the codebase and a proposed simplification.

[kylestratis]

Suggested change

	@overload
	@deprecated("The 'args' parameter is deprecated. Use 'arguments' instead.")

I'd avoid adding conventions that aren't used elsewhere in the SDK.

[inaku-Gyan]

Thank you for your feedback!
Personally, I felt it might be more consistent to rename args to arguments, since the original method ClientSession.call_tool uses arguments as its parameter name, so I added the deprecation warning. But per your suggestion, I reverted the changes in commit 4b9546d (#1576).

[kylestratis]

Suggested change

@overload

[kylestratis]

session_params should follow the pattern of server_params and be required or at least default to an empty session_params object (I prefer the former for consistency's sake). This will make _establish_session() able to take session_params as a required argument, removing the need to check if session_params() exists and having different calls to enter_async_context() in lines 322-328.

[inaku-Gyan]

The default value is changed into ClientSessionParameters() as required in commit 4ab9757 (#1576).