How to fix MCP tools not showing in Cursor

The most common cause is invalid JSON in your .cursor/mcp.json file. A single trailing comma, missing quote, or mismatched brace will silently prevent all MCP servers from loading. Cursor does not always show a clear error for JSON syntax issues. Open the file and validate it manually or with a JSON linter. Pay special attention to trailing commas after the last item in objects and arrays — JSON does not allow them.

1// Check your .cursor/mcp.json file
2// WRONG — trailing comma breaks JSON
3{
4  "mcpServers": {
5    "github": {
6      "command": "npx",
7      "args": ["-y", "@modelcontextprotocol/server-github"],
8    }
9  }
10}
11
12// RIGHT — no trailing comma
13{
14  "mcpServers": {
15    "github": {
16      "command": "npx",
17      "args": ["-y", "@modelcontextprotocol/server-github"]
18    }
19  }
20}
21
22# Validate from terminal:
23cat .cursor/mcp.json | python3 -m json.tool

Cursor shows MCP server connection status in the bottom status bar or in the settings. Look for the MCP indicator — a green dot means connected, red or absent means disconnected. You can also check by opening Cursor's command palette (Cmd+Shift+P) and searching for 'MCP' to see server status. If the server shows as disconnected, the server process may have crashed or failed to start.

1# Steps to check MCP status in Cursor:
2# 1. Open Command Palette: Cmd+Shift+P (macOS) or Ctrl+Shift+P (Windows)
3# 2. Type: "MCP" or "Model Context Protocol"
4# 3. Look for server status options
5# 4. Check if your server shows as connected
6
7# Alternatively, check Cursor's Output panel:
8# 1. View → Output (or Cmd+Shift+U)
9# 2. Select "MCP" from the dropdown
10# 3. Look for connection errors

Cursor reads the mcp.json file at startup or when the window reloads. If you edited the config while Cursor was running, the changes may not have been picked up. Reload the window using Cmd+Shift+P then typing 'Reload Window'. For stubborn cases, quit Cursor entirely and reopen it. This forces a fresh read of the config file and a fresh connection attempt to all servers.

1# Reload Cursor window:
2# 1. Cmd+Shift+P (macOS) or Ctrl+Shift+P (Windows)
3# 2. Type: "Developer: Reload Window"
4# 3. Press Enter
5
6# If that does not work, fully quit and reopen Cursor

If the server connects but reports zero tools, Composer has nothing to show. Test the server independently using MCP Inspector to confirm it actually exposes tools. Some servers only expose resources or prompts, not tools. Others may require specific environment variables to initialize their tool list. Run the server with MCP Inspector and verify tools appear there.

1# Test with MCP Inspector
2npx -y @modelcontextprotocol/inspector
3
4# In the Inspector web UI:
5# 1. Enter your server command
6# 2. Click Connect
7# 3. Check the Tools tab — tools should be listed
8# 4. If no tools appear, the server has none registered

Cursor has a soft limit of approximately 40 tools across all connected MCP servers. If you have many servers or servers that expose dozens of tools each, some tools may be silently dropped. The fix is to reduce the number of connected servers or configure servers to expose fewer tools. Prioritize the servers you use most often. If your workflow requires many MCP tools and you need help designing an efficient configuration, the RapidDev team can help optimize your setup.

1// Example: connect only the servers you need
2// Instead of 5 servers with 50+ total tools:
3{
4  "mcpServers": {
5    "github": {
6      "command": "npx",
7      "args": ["-y", "@modelcontextprotocol/server-github"]
8    },
9    "filesystem": {
10      "command": "npx",
11      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path"]
12    }
13  }
14}
15// Keep total tools under ~40 for best results