Agent Callback Mailbox MCP Server

by inversolabs Your server? Claim it

not responding

Agent Callback Mailbox is listed as active in the registry but did not answer our last check.

Paid replay-safe callback inboxes for asynchronous agent tasks with structured MCP results.

Uptime history 28 days of history · worst day 0%

28 days agonow

0.0%

Uptime 24h

0 of 90 checks

—

Tools

hidden behind auth

85 ms

Response time

average over 24h

open, no key

Access

streamable-http

Agent Callback Mailbox does not always answer

Over the last week it answered 0.0% of our checks. We check every 15 minutes, so you hear about the next outage within the hour — not from your users.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 12 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add agent-callback-mailbox --transport http https://callbacks.inversolabs.us/mcp

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "agent-callback-mailbox": {
      "url": "https://callbacks.inversolabs.us/mcp"
    }
  }
}

~/.codex/config.toml

[mcp_servers.agent-callback-mailbox]
url = "https://callbacks.inversolabs.us/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "agent-callback-mailbox": {
      "url": "https://callbacks.inversolabs.us/mcp"
    }
  }
}

.vscode/mcp.json

{
  "mcpServers": {
    "agent-callback-mailbox": {
      "url": "https://callbacks.inversolabs.us/mcp"
    }
  }
}

Endpoints

URL	Transport	State	Latency	Checked
https://callbacks.inversolabs.us/mcp	streamable-http	answering	85 ms	12 min ago

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Agent Callback Mailbox — questions

Answers built from our own checks of this server.

Is Agent Callback Mailbox working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 0 of 90 checks got a reply (0.0%), average response time 85 ms. The bar chart above shows every period we have measured.

The registry lists Agent Callback Mailbox as active — why does it not respond?

The official MCP registry stores what the author submitted; it does not verify that the server still runs. We check the endpoint ourselves, and this one does not answer. Catalogues that copy the registry without checking will show it as working.

How do I connect Agent Callback Mailbox?

Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does Agent Callback Mailbox need an API key?

No. Agent Callback Mailbox completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. This is what we observed, not what the docs claim.