[BUG] Claude Code and VS Code extension are not able to see all tools from an MPC

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?

Claude Code on version 2.1.296 can not access tools from an MPC that were working in previous version.

I'm using the Elastic Security MPC which exposes 44 tools, Claude Code reports only 11 tools.

What Should Happen?

Claude Code should have access to all tools on the MPC as it has on the pervious version.

Error Messages/Logs

There are no errors being show, it just reports that it cannot find tools that were previously used in skills and other actions.

If a Skill try to call a tool that is now unavailable it will show an error about it.

Steps to Reproduce

Replicating this requires an Elasticsearch Security Deployment and the configuration of the Security MCP from here.

Just asking claude how many tools it can see would replicate the issue.

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.278

Claude Code Version

2.1.296

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

MPC Showing all tools
<img width="453" height="452" alt="Image" src="https://github.com/user-attachments/assets/60614ffe-3ae0-48ec-a39c-7c6202d0e0ba" />

Claude answer showing that it can only see 11 tools.
<img width="2105" height="718" alt="Image" src="https://github.com/user-attachments/assets/df7ac082-ee0d-417c-8ffb-94d88347d979" />

Claude answer showing that it can see all tools when extension is on version 2.1.278
<img width="2080" height="370" alt="Image" src="https://github.com/user-attachments/assets/0fe108bf-92f9-4c3d-b9c2-b8c65b16fd8a" />