I experience exactly the same issue since yesterday night (~12 hours ago) trying to run an agent with Slack and Notion MCPs. And it still persists. At the same time the status of both Cursor and Anthropic seems to be at full availability.
Here someone has experienced a similar issue due to an MCP being enabled. But I am not sure it is related. Do you have any MCPs enabled?
UPD: At least on my side it seems to be related to the context size of the conversation. I do not have this issue when conversation begins, but at some point when I get a large response from an MCP server, it shows this error.