Type generics for CallToolResult - Require 'structuredContent' if 'outputSchema' defined.

[KKonstantinov]

The structuredContent tool output is currently not utilizing Typescript's capabilities and the check is performed only runtime.

If outputSchema is defined, as per the implementation, structuredContent is required in the response.

Motivation and Context

Mitigating runtime-only handling and proper type checking when outputSchema is defined.

How Has This Been Tested?

The changes are in types only - the results of the PR can be observed in tests, //@ts-expect-error has to be added now when testing for tools defined with outputSchema and not returning structuredContent.

Breaking Changes

No need, only if they had a runtime error anyways will they get a type error.

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

[KKonstantinov]

Please review, but this could be further improved by not allowing "structuredContent" at all when "outputSchema" is defined.

Currently, it'll only generate a typecheck error if "outputSchema" is defined but "structuredContent" is missing, but it will not error when "structuredContent" is returned and "outputSchema" wasn't defined in the first place. (e.g. if the user forgot by accident).

cc @ihrpr