What is postbag?
postbag is a MCP server by parasxos that letters between existing Claude Code and Codex sessions on one machine: join a named bag, send through each agent's native input, read one append-only ledger, leave when done. It is listed under Developer tools and has 11 GitHub stars.
| Type | Mcp server |
|---|---|
| Author | parasxos |
| Repository | parasxos/postbag |
| Popularity | 11 GitHub stars |
| Category | Developer tools |
| Security | Review before installing (72/100) |
| Rank | #1,636 of 4,418 MCP servers; #373 in Developer tools |
| License | MIT |
| Last commit | 2026-10-03 |
| Runs | Locally |
| Language | Python |
| Platforms | macOS, Linux |
Is postbag safe to install?
postbag scores 72/100 on the MCPMods security check: Review before installing. Things to review: can take actions such as send, write or deploy; executes code or shell commands. It passed 3 of 6 checks.
MCP server results come from listing signals: who publishes it, where your data goes and what it can do. The code itself is not scanned yet.
| Check | Result |
|---|---|
| Community-built server | Note |
| Runs on your machine only | Pass |
| No credentials mentioned | Pass |
| Can take actions such as send, write or deploy | Review |
| Executes code or shell commands | Review |
| Source on GitHub | Pass |
How do I install postbag?
- Find the launch command. The README says how the server starts (npx, uvx, docker or a remote URL) and which API keys it needs.
https://github.com/parasxos/postbag
- Add it to Claude Code. Replace the part after -- with the command from the README. Remote servers use --transport http with a URL.
claude mcp add postbag -- <command from README> claude mcp add --transport http postbag <server-url>
- Check it connected. This lists your MCP servers and their status.
claude mcp list
Or ask Claude to set it up
Paste this into Claude Code and it installs postbag for you:
Add the "postbag" MCP server from https://github.com/parasxos/postbag to Claude Code. Read its README for the launch command and any API keys I need, run claude mcp add, then check that it connects.