Agent Callback Mailbox

Overview

Agent Callback Mailbox is an MCP server that provides paid replay-safe callback inboxes for asynchronous agent tasks, delivering structured MCP results. Instead of manually managing callbacks across tools, AI assistants can directly invoke Agent Callback Mailbox as a set of callable tools within the Model Context Protocol.

The server runs as a hosted remote endpoint at https://callbacks.inversolabs.us/mcp with no local installation required. It requires no authentication to connect and is currently at release v0.1.54.

Agent Callback Mailbox belongs in the AI & Agents category on mcp.site and works with any MCP client including Claude Desktop, Claude Code, Cursor, VS Code, Windsurf, and Zed. If you maintain this server, claim your listing to verify ownership and keep its information current.

Installation

Settings → Connectors → Add custom connector
Name: Agent Callback Mailbox
URL:  https://callbacks.inversolabs.us/mcp