Model Context Protocol (MCP) is an open standard through which an agent gains access to external systems: databases, APIs, issue trackers and any other services. EONYX has a built-in MCP client based on the official Go SDK (modelcontextprotocol/go-sdk) — servers are described right in eonyx.json and their tools show up for the model alongside the built-in ones.

Hooks are shell commands that EONYX runs around tool calls: before (before) and after (after). They are a convenient way to bolt on auto-formatting, auditing, checks and guardrails without touching the agent’s code.

Besides the interactive TUI, EONYX can run headless — perform a task and exit. That is what you need for scripts, pipes and CI: predictable output, JSON events and meaningful exit codes.

Features are nice, but it is more interesting to see them at work. A few practical scenarios: how to phrase the task and which EONYX techniques to turn on. The prompts are deliberately plain.