mtl-agents-mcp

MCP server that lets local Claude Code and Codex sessions see and message each other.

You run Claude Code in one terminal and Codex in another. Each one only knows its own session. With this server, any session can ask "what did the Codex review find?" or "how far is the migration in the other Claude session?" and get an answer.

Features

• list_sessions: recent Claude Code and Codex sessions, with title, folder and whether they are running.

• read_session: the last messages of a session (text only, no tool calls). Cheap and read-only.

• ask_session: send a question to another session and wait for the answer.

How ask_session delivers a message:

An idle Claude Code session only answers after someone types in it. A busy one answers when its current turn ends.

Related MCP server: claude-intercom-mcp

Quick Start

Prerequisites

• Python 3.10+ and Poetry

• Claude Code and/or Codex CLI (codex queue needs a recent Codex version)

• jq for the hook install script

• macOS or Linux

Installation

git clone https://github.com/msmenzyk/mtl-agents-mcp.git
cd mtl-agents-mcp
poetry install

Register the server in Claude Code:

claude mcp add -s user mtl-agents -- bash -c "cd $PWD && poetry run python -m mtl_agents_mcp"

Register it in Codex (~/.codex/config.toml, use your real path):

[mcp_servers.mtl-agents]
command = "bash"
args = ["-c", "cd /path/to/mtl-agents-mcp && poetry run python -m mtl_agents_mcp"]
tool_timeout_sec = 300

Install the inbox hook, so running Claude Code sessions can receive messages. It adds itself to UserPromptSubmit and Stop in ~/.claude/settings.json and keeps a backup:

./hooks/install_claude_hook.sh

Restart your sessions so they load the new tools.

Usage

In any Claude Code or Codex session:

Use mtl-agents to list my running sessions.
Read the last 5 messages of the Codex session "Review the login flow".
Ask the Claude session in my-api how many tests still fail.

Where it reads from

• Claude Code: ~/.claude/projects/*/*.jsonl, running sessions from ~/.claude/sessions/<pid>.json

• Codex: ~/.codex/sessions/**/rollout-*.jsonl, titles from ~/.codex/session_index.jsonl. A Codex session counts as running when its log changed in the last 15 minutes.

• Inbox for Claude Code: ~/.agents/inbox/<session-id>/

These are internal formats of both tools and can change between versions. If a tool update breaks parsing, please open an issue with your versions.

Development

git clone https://github.com/msmenzyk/mtl-agents-mcp.git
cd mtl-agents-mcp
poetry install
poetry run pytest
poetry run ruff check . && poetry run ruff format --check .

Tests use fake session stores in a temp folder and never touch your real sessions.

Contributing

Contributions are welcome! Please read CONTRIBUTING.md before submitting a PR.

Security

This server reads every session transcript of your user, and ask_session can start agent runs in other projects. Read the threat model in SECURITY.md. To report a vulnerability, see the same file.

License

This project is licensed under the MIT License. See LICENSE for details.