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mcp/harbor
Claude Code

Letterbox for Claude Code

io.github.dovahkiin-v/letterbox

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

client:Claude Code transport:stdio runtime:pypi

Install Letterbox in Claude Code

run in your project directory

Held in this page only — never stored, logged, or sent anywhere but back to your screen. 

claude mcp add letterbox -e LETTERBOX_CHANNEL=<LETTERBOX_CHANNEL> -e LETTERBOX_SENDER=<LETTERBOX_SENDER> -e LETTERBOX_INSTANCE_ID=<LETTERBOX_INSTANCE_ID> -- uvx letterbox

Adds it for this project only. Append --scope user to make it available everywhere. Claude Code docs

Letterbox in other clients

Letterbox MCP server