[BUG] Claude code does not support MCP protocol version 2025-06-18 needed by Lens Studio and others

[mspertus]

Preflight Checklist

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

What's Wrong?

When I try to connect to Snap Lens Studio's MCP server from claude code, it fails to connect. After much debugging (with Claude code's assistance), we determined that the problem is that Lens Studio uses MCP protocol version 2025-06-18 while Claude Code apparently only goes up to MCP protocol version 2024-11-05.

What Should Happen?

Claude should be able to use MCP servers on protocol 2025-06-18. For example, the following curl statement works.

curl --location 'http://localhost:8732/mcp' \
--header 'Content-Type: appllication/json' \
--header 'Authorization: Bearer ...w37PVy' \
--data '  {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2025-06-18",
      "capabilities": {},
      "clientInfo": {
        "name": "postman-test",
        "version": "1.0"
      }
    }
  }'

Error Messages/Logs

Steps to Reproduce

1. Launch Lens Studio (or anything else on 2025-06-18)
2. AI Assistant/MCP/Configure Server/Start Server
3. Get config from AI Assistant/MCP/Copy MCP Configuration
4. Install it in Claude Code
5. Claude code will fail to connect

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

No response

Claude Code Version

2.1.2

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

No response

[mspertus]

To be honest, I was a little surprised by this since I would have expected Claude Code to track MCP development more closely. Is it possible there is some setting I missed? Here is the Claude Code discussion that led to filing this issue (lines beginning with ● are Claude and lines beginning with > are me)

● The Lens Studio MCP server works fine - it has 77KB worth of tools available. The problem is a protocol version mismatch:
  ┌────────────────────────┬───────────────────────┐
  │       Component        │   Protocol Version    │
  ├────────────────────────┼───────────────────────┤
  │ Lens Studio MCP Server │ 2025-06-18 (required) │
  ├────────────────────────┼───────────────────────┤
  │ Claude Code MCP Client │ 2024-11-05 (likely)   │
  └────────────────────────┴───────────────────────┘
  Claude Code is sending an older protocol version that Lens Studio rejects. This is a compatibility issue between the two.

  Options:
  1. Check for Claude Code updates - A newer version may support 2025-06-18
  2. Report the issue - File at https://github.com/anthropics/claude-code/issues requesting support for protocol version 2025-06-18
  3. Check Lens Studio - See if there's an option to use an older MCP protocol version

  For your Postman testing, use protocol version 2025-06-18 and it will work.

  Sources:
  - https://developers.snap.com/lens-studio/features/lens-studio-ai/developer-mode
  - https://developers.snap.com/lens-studio/features/lens-studio-ai/custom-prompt-for-mcp

✻ Crunched for 2m 32s

❯ Can you give me a curl to put in postman?

● Here's the working curl command:

  curl -X POST http://localhost:8732/mcp \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer <snip>37PVy" \
    -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"postman-test","version":"1.0"}}}'

  In Postman you can use Import > Raw Text and paste that, or set it up manually:

  - POST http://localhost:8732/mcp
  - Headers:
    - Content-Type: application/json
    - Authorization: Bearer iKWBzakrUgOS7FsRao8YnB3-_kEcw8j112wzJXtWZz16_633Az-N2PnrrIw37PVy
  - Body (raw JSON):
  {
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2025-06-18",
      "capabilities": {},
      "clientInfo": {
        "name": "postman-test",
        "version": "1.0"
      }
    }
  }

❯ That worked. Can Claude use it?

● Not currently. Claude Code's MCP client is sending protocol version 2024-11-05, but Lens Studio requires 2025-06-18. That's why you see "Failed to connect" - the server rejects the handshake.

  Let me check what version of Claude Code you're running:

● Bash(claude --version)
  ⎿  2.1.2 (Claude Code)

● You're on Claude Code 2.1.2. The MCP protocol version it uses (2024-11-05) predates what Lens Studio expects (2025-06-18).

  Your options:

  1. Update Claude Code - Check if there's a newer version:
  claude update
  2. File an issue - Request support for the newer protocol at https://github.com/anthropics/claude-code/issues
  3. Wait for Lens Studio - Snap might add backwards compatibility for older protocol versions

  Want me to check if there's an update available?

❯ What is the newest version of claude code?

● Web Search("Claude Code latest version 2025 2026 changelog")
  ⎿  Did 1 search in 21s


● You're already on the latest version (2.1.2). So the MCP protocol version 2025-06-18 that Lens Studio requires isn't supported yet.

  Your best bet is to file an issue at https://github.com/anthropics/claude-code/issues requesting support for MCP protocol version 2025-06-18 - mention that Lens Studio requires it.

[lcartwright-sc]

Thanks for the bug report @mspertus! We just looked into this on the Lens Studio side, and we're going to prepare a fix.

The issue appears to have started in CC 2.0.71, due to CC updating to MCP version 2025-11-25. LS currently only supports 2025-06-18. This is the first protocol update since we've released the MCP server, and it looks like we're not handling protocol negotiation correctly.

Until we have a Lens Studio update available, I'd recommend downgrading Claude Code to version 2.0.70.

[lcartwright-sc]

I just wanted to provide an update on this. We've just released patch updates (5.17.2 & 5.15.3) to Lens Studio that add support for the latest version of the MCP protocol, and support for negotiating the connection version to prevent problems like this in the future. You can download the updated versions at: https://ar.snap.com/download and https://ar.snap.com/spectacles.

Thanks for reporting the issue, and I hope you have fun building things with it!

[github-actions]

Closing for now — inactive for too long. Please open a new issue if this is still relevant.

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.