Add group to tools

Hello, I would like to add a group request endpoint, and mark which group it belongs to when registering tools. When using the SSE endpoint, describe the group in the path or parameters. When the client pulls the tool list, it returns the tools of the specified group (if no group is specified, all are returned).

I expect to solve the problem:

1 When a server has many tools, I don't want to use multiple endpoints to group these tools, which is simpler when used in a framework like Spring.
2 Configure different groups to express different agents by obtaining different tool lists.

Note: Alternatively, add a group by interface to handle the group names passed by the SSE endpoint. This interface receives the group name and tools list context, and returns the tools list corresponding to the group name.

Start by tracing the existing SSE endpoint, tool-registration flow, and tool-list response. Review how request parameters and registered tools are currently handled before deciding between endpoint changes and a grouping interface. Done means a server can register tools by group, request a group through SSE, and receive either that group or all tools when no group is specified.