Implement SEP-973: Icons and metadata support

[dsp-ant]

Description

This issue tracks the implementation of SEP-973 which adds support for icons and additional metadata for Implementations, Resources, Tools, and Prompts.

Summary

SEP-973 introduces optional icon support and website URLs to help clients visually identify MCP servers and their capabilities. This includes:

• Icons for server implementations (multiple sizes supported)
• Icons for individual resources, tools, and prompts
• Website URLs for documentation linking

Implementation Requirements

• Add optional icons field to server metadata (supporting multiple MIME types and sizes)
• Add optional websiteUrl field for documentation links
• Update Resources, Tools, and Prompts to support icon metadata
• Ensure backward compatibility (all fields are optional)

Reference

• PR: SEP-973: Expose additional metadata for Implementations, Resources, Tools and Prompts modelcontextprotocol#955
• Specification changes will be merged soon

Note

Please add this issue to project: 2025-09-18 SDK Implementation

[Bellangelo]

I can take a look at this after we finish with this PR: #42. It is unrelated but I don't want to split my focus between 2 different PRs at the moment.

[WendellAdriel]

@dsp-ant @Bellangelo if you want to, I could work on this.
I can start a draft PR to get some input from you and go from there.