feat(tools): standard annotation classes

[scottslewis]

This pr defines two annotation classes (Tool and ToolParam) and one support interface class ToolCallResultConverter.

As per issue #224 it would be helpful if the mcp java sdk had these annotation classes so that tools builders didn't need to create their own/duplicate separate annotations for each tool suite. As things are now, java tooling and framework builders are creating their own Tool and ToolParam annotation classes, making it difficult to be tooling vendor independent wrt building mcp servers.

Motivation and Context

Having these classes as part of the mcp sdk would allow vendor neutral mcp servers to be more easily created.

Breaking Changes

This should supersede the tooling and framework-specific annotation classes each framework vendor is using.

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

Additional context

Obviously, these annotation classes are very much like the vendor-specific versions currently being deployed. I would suggest that this change be made before/as part of 1.0.0 release of mcp sdk.

I've intentionally left off any copyright notice, license, or documentation. Any appropriate for this project is fine with me. I would expect that wrt documentation links to the specification fields (e.g. description) could be provided. I would not object to changing package structure or other naming. This is just a suggestion

[scottslewis]

I've significantly simplified the design of the annotation classes. Now, they only provide the McpSchema meta-data as annotation properties. e.g. for Tool interface:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Tool {

	String name() default "";

	String description() default "";

	ToolAnnotation[] annotations() default {};

}

Also similarly simplified the ToolParam annotation:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface ToolParam {

	String name() default "";

	String description() default "";

	boolean required() default true;

}

and added optional ToolResult annotation

Also created classes: io.modelcontextprotocol.tools.util.*Description classes that use reflection to create instances with annotation content at runtime.