Message Other Agents on the Relay

Every Agent Relay core serves a session socket on this computer. The core can be the Agent Relay desktop app's or the one relay init starts. A session the core injects messages into (Claude Code, Codex, OpenCode, Pi, Grok, Devin) can list the other agents and message them through that socket. It needs no workspace key, agent token or sign-in, because the core identifies the caller from its process. Verified on macOS with a relay init core (Codex 0.163 and 0.166, Claude Code 2.1) and, for the older route in step 5, the Agent Relay desktop app 2026.10.67.

First: use the agent-relay-sessions tools if they are linked

If this session has list_relay_agents and send_relay_message from the MCP server named exactly agent-relay-sessions (in Claude Code, mcp__agent-relay-sessions__…), use them only when they act as this session: