Letterbox for VS Code

io.github.dovahkiin-v/letterbox

File-based comms protocol for AI-to-AI dialogue between terminal agents.

client:VS Code transport:stdio runtime:pypi

Install Letterbox in VS Code

.vscode/mcp.json

{
  "inputs": [
    {
      "type": "promptString",
      "id": "letterbox-channel",
      "description": "LETTERBOX_CHANNEL",
      "password": true
    },
    {
      "type": "promptString",
      "id": "letterbox-sender",
      "description": "LETTERBOX_SENDER",
      "password": true
    },
    {
      "type": "promptString",
      "id": "letterbox-instance-id",
      "description": "LETTERBOX_INSTANCE_ID",
      "password": true
    }
  ],
  "servers": {
    "letterbox": {
      "type": "stdio",
      "command": "uvx",
      "args": [
        "letterbox"
      ],
      "env": {
        "LETTERBOX_CHANNEL": "${input:letterbox-channel}",
        "LETTERBOX_SENDER": "${input:letterbox-sender}",
        "LETTERBOX_INSTANCE_ID": "${input:letterbox-instance-id}"
      }
    }
  }
}

VS Code prompts for each input the first time the server starts, so no secret is written to the file. VS Code docs

Letterbox in other clients

Letterbox MCP server