Add title to tools, prompts and resources

[jdnvn]

This implements the spec change from modelcontextprotocol/modelcontextprotocol#663 to improve user experience by allowing servers to provide a human-friendly names, called "title", for tools, prompts and resources.

Motivation and Context

There is a worklog to apply the changes to all SDKs but Ruby didn't seem to be listed, so figured I'd go ahead and open a PR!

How Has This Been Tested?

I've tested the gem locally with each object type from my own Rails MCP server. I also tested both scenarios - with title added vs omitted and both worked as expected.

Breaking Changes

No, this is an optional field

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

When a title is not added, it will not be included in the response. I assume this is the expected behavior here vs returning a blank title? That's my intuition but curious to hear other's thoughts.

[topherbullock]

thanks!