Codex CLI 0.134.0: Read-Only MCP Tools Run Concurrently via readOnlyHint — Parallel Execution Cuts Agent Latency

OpenAI Codex Changelog·medium signal

OpenAI Codex CLI now lets MCP tools that advertise readOnlyHint execute in parallel rather than sequentially. When an agent chains multiple read-only lookups (file reads, search, DB queries), they all fire simultaneously. Also ships: local conversation history search with case-insensitive matching, --profile as single source of truth for profile selection, and per-server MCP environment targeting with OAuth for streamable HTTP servers.