In Cursor version `0.47.8`, agent mode incorrectly prefixes MCP tool names with `mcp_servername_`, causing tools to fail

[michiosw]

Forum Check:
Checked the forum; this issue has not been reported previously.

Bug Description:
When adding an SSE MCP server in Cursor version 0.47.8 using the following configuration:

"cobrowser": {
  "url": "..."
}

Cursor successfully connects and lists available tools (tool_x, tool_y) in the Visual MCP settings.
However, when using agent mode to invoke these tools, Cursor incorrectly prefixes the tool names, calling mcp_cobrowser_tool_x instead of directly calling tool_x. This results in the tools not being found.

Steps to Reproduce:

1. Configure an SSE MCP server in Cursor (0.47.8) with:

   "cobrowser": {
     "url": "..."
   }
   

2. Confirm that Cursor connects and correctly lists the tools in Visual MCP settings.
3. Activate Cursor’s agent mode and request the agent to use tool_x.
4. Observe Cursor incorrectly attempting to invoke mcp_cobrowser_tool_x instead of the correct tool_x.

Screenshots or Recordings:

Operating System & Cursor Version:

• Operating System: macOS
• Cursor Version: 0.47.8

Blocks Cursor Usage:
Yes, this prevents the correct use of custom MCP tools via Cursor’s agent mode.

[giorgos3215]

Can confirm this is happening to me too. telling the AI to remove the prefix seems to visually atleast call the right tool, however in the backend its still calling with the prefix making it return tool not being found.

[vittorius]

Confirm that as well. Happened to me when I tried using the Github MCP server. The 1st Agent run was OK, but every subsequent one failed with this error.