[BUG] Plugin-provided MCP servers never registered — written to wrong config file

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?

When a Claude Code plugin that declares mcpServers is installed (at either user or local scope), the MCP server entry is written to ~/.claude/.mcp.json. However, the MCP runtime does not read this file
— it reads ~/.claude.json.

Result: Plugin-provided MCP servers never appear in claude mcp list and are never reachable, regardless of install scope.

Workaround: Manually add the server via claude mcp add, then patch ~/.claude.json to include any OAuth config that claude mcp add doesn't support as flags.

What Should Happen?

Expected behavior: Plugin MCP servers should be written to ~/.claude.json — under the user key for user-scoped installs, or under the project path key for local-scoped installs — matching the format
used by claude mcp add.

Error Messages/Logs

Steps to Reproduce

Prerequisites:

• A Claude Code plugin that declares mcpServers in .claude-plugin/plugin.json (e.g. the pingone-mcp plugin from a local marketplace)

Steps to Reproduce:

1. Add a local plugin marketplace:

claude plugin marketplace add /path/to/plugins

1. Install an MCP server plugin at local scope:

/plugin → select and install the MCP plugin

1. Configure the plugin when prompted (fill in URL, client ID, etc.)
2. Run /reload-plugins
3. Run claude mcp list

Verification: Manually adding the same server via claude mcp add writes to ~/.claude.json and the server immediately appears in claude mcp list.

Also reproduced at user scope — installing the plugin as user-scoped still writes to ~/.claude/.mcp.json, not ~/.claude.json.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.119

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_