Set up MCP in Codex

With the Codex CLI installed, run:

assign mcp setup codex

If you haven't run assign login, setup starts that flow first. It then registers https://mcp.assign.so/ in Codex and starts Codex's own authorization. Your existing browser session usually saves you from signing in again, but Assign still asks you to approve the Workspace and scopes.

CLI and MCP credentials are separate: Codex stores and refreshes its own revocable MCP credential, and the CLI's tokens are never copied. For read-only access:

assign mcp setup codex --scopes assign:read

• Setup reuses a compatible existing assign entry. If that name points to another URL, a local process or an environment bearer token, setup refuses to overwrite it. Inspect it with codex mcp get assign and remove it first.
• Only the production Assign host is supported.
• For a local stdio server instead of remote OAuth, pass --transport stdio. Codex then starts assign mcp serve, which uses the CLI's credential to request a short-lived, non-refreshable token that can't exceed its parent. Logging out or revoking the parent ends it. The bridge stays on the Workspace it first connected to, so restart the connection after assign workspace switch.
• --transport remote is the default. Setup won't replace an entry that uses a different transport.

See Connect a client for manual setup and the tool catalog.