Is your feature request related to a problem? Please describe.

MCP servers with many tools (50+) consume significant tokens listing all tool schemas. For example, a MySQL MCP server with 106 tools sends ~207KB (~54,600 tokens) on every initialization—even when the model only needs 2-3 tools. This creates unnecessary cost and latency for servers with comprehensive tool sets.

Describe the solution you'd like

Add Lazy Tool Hydration with two protocol changes:

1. minimal flag for tools/list: Return only tool names, categories, and summaries (~5K tokens) instead of full schemas
2. New tools/get_schema method: Fetch full schema on-demand for specific tools (~400 tokens each)

This provides 91% token savings while maintaining backward compatibility—servers without the capability continue to work unchanged.

Describe alternatives you've considered

• Pagination only: Doesn't reduce per-page token cost
• Server-side filtering: Still requires schema knowledge for filtering
• Schema compression: Limited gains, adds complexity

Additional context

• Reference implementation: mysql-mcp (lazy branch)
• Full RFC document: RFC-lazy-tool-hydration.md
• Measured savings: 91% reduction (54,604 → 4,899 tokens for 106 tools)
• Stages completed: Define ✅ Prototype ✅ Write ✅