claude-code - 💡(How to fix) Fix MCP tool schemas dropped after batch error array from restarted server [1 comments, 2 participants]

1. The server crashes during cleanup after the first response — the remaining calls return error arrays from the auto-restarted instance The client should re-fetch tool schemas (tools/list) when it detects a server restart or reconnection, so the agent can act on recovery hints in the error response (e.g. "call open_idb again"). Tool schemas are gone. The server's improved error message ("the server may have restarted — call open_idb again") is useless because the agent can't invoke open_idb without the schema.

TL;DR

The client should re-fetch tool schemas when detecting a server restart or reconnection to recover from lost cached tool schemas.

Guidance

• Investigate the client's reconnection logic to ensure it triggers a tool schema refresh after a server restart.
• Verify that the server's error response with recovery hints (e.g., "call open_idb again") is properly handled by the client to initiate schema re-fetching.
• Consider implementing a periodic tool schema refresh mechanism to mitigate the issue in cases where the client fails to detect a server restart.
• Review the client's caching strategy for tool schemas to determine if a more robust caching mechanism can be implemented to prevent schema loss during server restarts.

Example

No code snippet is provided as the issue does not contain sufficient technical details to create a specific example.

Notes

The provided workaround of manually running /mcp to force reconnection suggests that the issue is related to the client's ability to detect and respond to server restarts. However, without further information about the client's implementation, it is difficult to provide a more specific solution.

Recommendation

Apply workaround: Manually running /mcp to force reconnection is the most straightforward solution until a more robust client-side implementation can be developed to handle server restarts and tool schema caching.