types: Setting default value for method: Literal

[sreenaths]

method fields are literals that enforce a specific value. As the value is not set by default, we have to pass the correct value every time a model is instantiated.

Motivation and Context

This change simplifies model instantiation, as the method would be automatically set.
For example

    initialize_request = InitializeRequest(
        # method="initialize", - This wouldn't be required
        params=InitializeRequestParams(
            ...
        )
    )

How Has This Been Tested?

Existing tests work as expected, and a new test was added.

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• 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

None

[ochafik]

Hi @sreenaths, thanks for your PR!

I think this makes sense, could you please also remove the now-redundant method ctor args throughout the SDK? (mostly in {client,server}/session.py and tests)

[sreenaths]

Hi @ochafik,
Thank you so much for the review.
I have updated the PR to remove redundant method args.