agent-bridge-mcp

Discover and exchange text between your existing Claude Code and Codex sessions. The bridge uses your installed, authenticated clients; it needs no API keys and makes no model API calls. Messages can start work and consume client usage.

Requirements

Linux or WSL 2, Node.js 24+, Claude Code >= 2.1.224, and Codex with its app-server daemon running. Tested with Claude Code 2.1.312 and Codex CLI 0.165.0.

The bridge depends on undocumented Claude and Codex internals and may break on client updates. Run agent-bridge-mcp doctor first when something stops working.

Related MCP server: Switchboard

Install and connect

Install from GitHub; no account or SSH key is needed.

npm pack git+https://github.com/vstratful/agent-bridge-mcp.git
npm install -g ./agent-bridge-mcp-*.tgz && rm ./agent-bridge-mcp-*.tgz

Don't use npm install -g git+https://… directly: npm's global git install fails to build the package (tsc: not found). Packing first builds it in a normal clone.

Register in both clients using absolute paths:

claude mcp add --scope user --transport stdio agent-bridge -- "$(command -v node)" "$(npm root -g)/agent-bridge-mcp/dist/cli.js" serve
codex mcp add agent-bridge -- "$(command -v node)" "$(npm root -g)/agent-bridge-mcp/dist/cli.js" serve

Version managers can give a client a different, older Node; absolute paths keep both clients on the Node version used to install the bridge. Reconnect their MCP connections (/mcp) after registration or updates. Installation sends no messages. The bridge must run in the same host process namespace as the sessions.

agent-bridge-mcp doctor

Doctor reports PASS, WARN, FAIL or SKIPPED and fixes for non-passing checks; any FAIL exits with status 1. It checks metadata and configuration without sending messages or creating bridge files. Unsupported registration queries are SKIPPED and do not affect the exit code.

Using it

You don't call the bridge yourself. Talk to Claude or Codex as you normally would and ask it to message another session; the agent finds the session and sends the message with the bridge's tools. For example, you might type:

List my other Claude and Codex sessions.

Tell the Codex session working on billing-api that the response schema changed.

Ask the Claude session reviewing the auth PR for its findings.

Sessions are known by their names: a Claude session's name (set with /rename or chosen automatically) and a Codex thread's title. If two share a name, the agent uses the full session ID instead.

The message appears in the other session's conversation with a preview such as From billing-api (codex): The response schema changed. The receiving agent treats it as a message from another agent, not from you, so it may check with you before acting on it. To answer, ask that agent to reply; the reply comes back the same way. An idle session picks the message up straight away. A busy Claude reads it between steps; a busy Codex gets it when its current turn finishes.

The sending agent reports one of these:

• queued (to Codex) or submitted (to Claude): handed over. Neither means the other agent has read it yet, and a Claude session can be set to hold or refuse messages without the sender being told.

• unknown: it may or may not have been delivered. The agent won't resend it under a new ID, to avoid a duplicate; check the other session.

Security and limits

Local sessions must run as the same OS user. Sender IDs and names are claims; Claude shows the sending process's verified PID as a stronger signal. Messages are labelled as agent-originated text and cannot grant approval or change permissions. The bridge is not a security boundary between agents under the same OS account.

Closed Codex windows can leave threads messageable for 30 minutes with nobody watching. Message text appears in the Codex queue command's argv, readable by other local users unless /proc access is restricted. The journal retains message text for 30 days by default. No HTTP listener is opened. Native Windows, remote or cloud sessions, agent-team control messages and arbitrary command execution are outside this version. See verification and protocol details for tested behavior, hold/refuse rules, transport limits, sources and live checks.

Configuration

Uninstall

claude mcp remove --scope user agent-bridge
codex mcp remove agent-bridge
npm uninstall -g agent-bridge-mcp

Stop connected bridge processes before manually removing the configured state and runtime directories if you also want to delete retained messages and sockets.

License

MIT. See LICENSE.