What is agent-mailbox?
agent-mailbox is a Claude Code mod by charanjit-singh that mailboxes for Claude sessions: names, cross-profile messages that wake idle sessions, and a band with your account, context, and plan limits. It is listed under Cost & usage and has 2 GitHub stars.
| Type | Claude code mod |
|---|---|
| Author | charanjit-singh |
| Repository | charanjit-singh/ClaudeVsCodeMinimal |
| Popularity | 2 GitHub stars |
| Category | Cost & usage |
| Security | High risk (56/100) |
| Rank | #1,123 of 5,272 Claude Code mods; #203 in Cost & usage |
| Last commit | 2026-10-09 |
| Hooks | 8 events |
| Sees | every prompt, mcp__agent-mailbox__create_mailbox calls, mcp__agent-mailbox__leave_mailbox calls, mcp__agent-mailbox__list_mailboxes calls, mcp__agent-mailbox__list_peers calls, mcp__agent-mailbox__read_messages calls, mcp__agent-mailbox__select_mailbox calls, mcp__agent-mailbox__send_message calls, mcp__agent-mailbox__set_label calls |
| Draws on | AbovePrompt |
Is agent-mailbox safe to install?
agent-mailbox scores 56/100 on the MCPMods security check: High risk. Things to review: starts processes outside the sandbox; reads environment variables; watches every prompt or event. It passed 3 of 8 checks.
Mod footprints come from claude plugin validate, which lists every event a mod hooks and every API call it makes without running it.
| Check | Result |
|---|---|
| No network access | Pass |
| Starts processes outside the sandbox | Review |
| Writes no files or config | Pass |
| Reads environment variables | Review |
| Watches every prompt or event | Review |
| Drives Claude (model calls, prompts) | Note |
| Passes claude plugin validate | Pass |
| No license detected | Note |
API calls in its code
| Call | What it means |
|---|---|
$.clock.every | |
$.command.register | |
$.env.get | reads env vars |
$.fs.list | reads files |
$.fs.read | reads files |
$.process.run | runs processes |
$.prompt.submit | drives Claude |
$.session.cwd | |
$.session.usage | |
$.state.get | |
$.state.set | |
$.tool.register | drives Claude |
$.ui.resolve | draws interface |
$.ui.toast | draws interface |
How do I install agent-mailbox?
- Check your Claude Code version. Mods need Claude Code 2.1.287 or later and are on by default.
claude --version
- Read its footprint. This lists every event it hooks and every API call it makes, without running it.
git clone https://github.com/charanjit-singh/ClaudeVsCodeMinimal claude plugin validate ./ClaudeVsCodeMinimal/mod/agent-mailbox
- Install it. Run this in your terminal, then /reload-plugins in an open session.
git clone https://github.com/charanjit-singh/ClaudeVsCodeMinimal && claude --plugin-dir ./ClaudeVsCodeMinimal/mod/agent-mailbox
Or ask Claude to set it up
Paste this into Claude Code and it installs agent-mailbox for you:
Install the "agent-mailbox" Claude Code mod from https://github.com/charanjit-singh/ClaudeVsCodeMinimal/tree/main/mod/agent-mailbox. Run claude plugin validate on it first and show me what it can access before you enable it.