Qdrant MCP: -32602 Invalid request parameters in Cursor (stale client connection)

TL;DR: -32602 Invalid request parameters in Cursor, while the same server works in tests, is a stale client connection. Cursor cached the old schema or connection. Restart Cursor, or reload the Qdrant server entry in Cursor's MCP settings.

MCP error -32602: Invalid request parameters

Fix it

1. In Cursor, open Settings, navigate to MCP Servers, and reload or reconnect the Qdrant server entry.
2. If that does not clear it, fully quit and restart Cursor. MCP connections initialize at client startup.

3. Retry the tool call.

   Expected: the -32602 error is gone and tools execute normally.

When to use this

• The server works when tested directly (stdio test, inspector) but fails in Cursor with -32602.
• The error appeared right after you changed the server config or updated the server.

When NOT to use this

• The error happens everywhere, including direct tests. Then the request parameters genuinely are invalid. Check the tool schema.
• The error is -32603. That is a server-side failure, different problem.

Compatibility

• Any MCP server used through Cursor, including qdrant/mcp-server-qdrant.

Why it happens

MCP clients cache the tool list and schemas from when they first connected. If the server restarts with a changed schema (or the connection goes stale), the client keeps validating calls against the old schema and rejects them with -32602 before they ever reach the server. Reconnecting forces a fresh tools/list.

Edge cases

• If you run the server from source and rebuild often, expect this regularly. Reconnect after each rebuild.
• Multiple Cursor windows can hold different cached schemas. Restart all of them.
• The same staleness affects Claude Desktop and other clients. The fix is always: reconnect or restart the client.

The mcp-qdrant-custom troubleshooting guide (cedriccmh/mcp-qdrant-custom docs/TROUBLESHOOTING.md) documents this exact issue: Cursor MCP Tool Error with symptom MCP tool works in tests but shows error in Cursor, Error: MCP error -32602: Invalid request parameters. The listed causes are Cursor caching the old connection, the server restarted but Cursor not reconnected, or schema mismatch between Cursor and server. The fix is restarting Cursor to refresh the MCP server connection, or reloading/reconnecting the Qdrant server in Cursor settings. Source: https://github.com/cedriccmh/mcp-qdrant-custom/blob/HEAD/docs/TROUBLESHOOTING.md