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MCP (Model Context Protocol) servers provide additional tools to agents. Configure them per-project in .mux/mcp.jsonc.

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Configuration

You can either configure the servers in the UI (Ctrl+,): MCP Servers UI Or directly in the .mux/mcp.jsonc file in your project root: 
{
  "servers": {
    // Knowledge graph for persistent memory
    "memory": "npx -y @modelcontextprotocol/server-memory",
    // Browser automation and screenshots
    "chrome": "npx -y chrome-devtools-mcp@latest --headless",
  },
}
Each entry maps a server name to its shell command. The command must start a process that speaks MCP over stdio (NDJSON format).

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Slash Commands

Manage MCP servers directly from chat:
CommandDescription
/mcp add <name> <command>Add a new MCP server
/mcp remove <name>Remove an MCP server
/mcp edit <name> <command>Update an existing server’s command
Examples: 
/mcp add memory npx -y @modelcontextprotocol/server-memory
/mcp add chrome npx -y chrome-devtools-mcp@latest --headless
/mcp remove github
/mcp edit chrome npx -y chrome-devtools-mcp@latest --headless --isolated

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Scope

MCP servers have two scopes:
  • Configuration is per-project — The .mux/mcp.jsonc file lives in your project root and applies to all workspaces created from that project
  • Runtime instances are per-workspace — Each workspace runs its own server processes, so state in one workspace doesn’t affect another
This means you configure servers once per project, but each workspace (branch) gets isolated server instances with independent state.

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Behavior

  • Hot reload — Config changes apply on your next message (no restart needed)
  • Isolated — Server processes run in the workspace directory with its environment
  • Lazy start — Servers start when you send your first message in a workspace
  • Idle timeout — Servers stop after 10 minutes of inactivity to conserve resources, then restart automatically when needed

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Finding MCP Servers

Browse available servers at mcp.so or the MCP servers repository.

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Troubleshooting

If a server fails to start:
  1. Test the command manually — Run the command in your terminal to verify it works
  2. Check dependencies — Ensure required packages are installed (npx -y downloads on first run)
  3. Use the Test button — Settings → Projects shows connection errors inline