[BUG] Tools don't show up of mcp (using rmcp (rust))

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

MCP tools from rmcp (Rust) servers fail Zod validation

### Description
MCP servers built with the Rust rmcp SDK fail to load tools in Claude Code, while resources work fine. The error is:
[ERROR] MCP server "pop-mcp" Failed to fetch tools: [{
"expected": "record",
"code": "invalid_type",
"path": ["tools", 3, "inputSchema", "properties"],
"message": "Invalid input: expected record, received object"
}]

### Environment

• rmcp version: 0.12.0
• Server: https://github.com/r0gue-io/pop-mcp

### Steps to Reproduce

1. Configure an rmcp-based MCP server in Claude Code
2. Start Claude Code
3. Observe tools fail to load, resources work

### Expected Behavior
Tools should load since the JSON schema format is valid MCP.

### Notes

• Context7 (JavaScript MCP server) works fine
• The JSON output from both servers appears structurally identical
• Schema transformation to match context7 format doesn't resolve the issue

That removes all local paths and personal info. The public GitHub repo link is fine to include.

What Should Happen?

Tools should show

Error Messages/Logs

Steps to Reproduce

Create an mcp tool with rmcp

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

-

Claude Code Version

2.1.5

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_