claude-code - 💡(How to fix) Fix MCP plugin tools override explicit CLAUDE.md instructions [1 comments, 2 participants]

The Playwright MCP plugin uses a single shared Chrome profile directory. When multiple Claude Code sessions are running, only one can hold the SingletonLock. The others get an unrecoverable error — even "Close browser" fails because the lock belongs to a different process. There's no --isolated flag exposed through the MCP interface to work around this.

TL;DR

Disable the Playwright MCP plugin to ensure Claude follows explicit instructions in CLAUDE.md instead of pattern-matching the user's intent.

Guidance

• Verify that the issue is resolved by disabling the Playwright MCP plugin and checking if Claude uses the open command via Bash as specified in CLAUDE.md.
• To mitigate the secondary issue of Playwright cross-session conflicts, consider running Claude Code sessions in isolated environments or exploring alternative browser plugins that do not use a shared profile directory.
• Check the CLAUDE.md instructions for any inconsistencies or ambiguities that may be contributing to the model's behavior.
• Investigate the possibility of updating the Playwright MCP plugin to a version that exposes an --isolated flag or provides a similar workaround for cross-session conflicts.

Example

No code snippet is provided as the issue is related to plugin configuration and model behavior rather than code syntax.

Notes

The provided solution assumes that disabling the Playwright MCP plugin is a viable workaround. However, this may not be a suitable long-term solution, and further investigation into the model's behavior and plugin configuration may be necessary.

Recommendation

Apply workaround: Disable the Playwright MCP plugin to ensure Claude follows explicit instructions in CLAUDE.md. This is a temporary solution to mitigate the issue until a more permanent fix can be implemented.