CodexMCP is a lightweight MCP (Model Context Protocol) server that acts as a bridge between Claude Code and OpenAI's Codex CLI. It exposes a single `codex` tool that allows MCP clients to invoke Codex CLI sessions programmatically over stdio. The server handles session persistence via UUIDs, supports multi-turn conversations, parallel execution, and sandboxed workspace modes. The core implementation consists of a subprocess wrapper that streams JSON lines from Codex's `exec` command, parses agent messages and thread IDs, and returns structured results. It also includes Windows-specific command-line escaping to handle prompt injection safely. The codebase is minimal (two source modules plus a CLI entry point) but demonstrates solid patterns for wrapping external CLI tools in the MCP protocol, with graceful shutdown handling and error reporting. It does not include tests or CI/CD configuration, but the architecture is clean and focused.