Antigravity CLI is a terminal agent Google announced at I/O on May 19, 2026. Written in Go (versus Gemini CLI's Node.js), its binary is called agy, and it shares the same agent harness as the desktop Antigravity 2.0. It is also Gemini CLI's successor — the personal-tier Gemini CLI service ends on June 18, 2026.
goose is an open-source AI Agent maintained by the Linux Foundation's AAIF, supporting 15+ LLM providers and 70+ MCP extensions, built with Rust as a Desktop App + CLI + API. It positions itself as a vendor-neutral, self-hostable alternative to Claude Code.
MCP is not going away, but its effective scope is narrower than most people think. For local development, CLI and raw API almost always beat MCP. MCP's truly irreplaceable niche is the narrow gap of 'cross-agent shared local tool layer.'
Agent CLIs are not smarter autocomplete tools -- they are AI agents that can read your codebase, execute multi-step tasks, and operate in real environments. Claude Code, Codex CLI, Gemini CLI, OpenCode, Aider, Pi, Kiro, Amp, Cursor CLI... the tools keep multiplying, but they all share a common set of design principles -- understanding these principles is how you actually get good at using them.
Claude Code is Anthropic's agentic coding tool that runs in the terminal, IDEs, Slack, GitHub, and on the web. Its core extension system has six layers: CLAUDE.md (persistent context), Skills (on-demand workflows), Hooks (deterministic automation), Subagents (isolated delegation), MCP (external tool connections), and Agent Teams (multi-agent collaboration).
Codex CLI is OpenAI's open-source terminal coding agent built in Rust. It supports MCP, subagents, image input, and code review. Paired with the codex-1 (o3-optimized) or GPT-5-Codex model, it can read, write, and execute code directly on your local machine.
Gemini CLI is Google's open-source terminal AI agent (Apache 2.0). ⚠️ Announced end-of-service on 2026/06/18 — official migration path is Antigravity CLI. Free accounts get 60 requests/minute and 1,000 requests/day; Skills, Hooks, and Subagents all carry over.
OpenCode is an open-source AI coding agent built in Go (95K+ GitHub stars) with a built-in TUI, support for 75+ LLMs, LSP integration, Vim-style editing, and SQLite session management. Free, no subscription required — works with local or cloud models.
Pi is a minimalist coding agent built in TypeScript by Mario Zechner, featuring just 4 core tools (read, write, edit, bash) and a 300-word system prompt. It's extensible via Extensions, Skills, and Prompt Templates, runs on the Bun runtime, and ships with built-in Ollama support via `ollama launch pi`.
When processing requests, Claude Code randomly displays one of 185 built-in verbs (like Thinking, Brewing, Clauding), then picks one of 8 completion verbs with elapsed time. You can customize these via spinnerVerbs in settings.json, using either replace or append mode. All data in this post is verified directly from cli.js source code.
Claude Code has five permission modes: default (confirm each step), acceptEdits (auto-accept edits), plan (read-only planning), auto (background AI classifier review), and bypassPermissions (YOLO, skip everything). Switch with Shift+Tab or configure via settings.json. Auto mode is the sweet spot — no step-by-step confirmations, but with safety guardrails.
Once SSH config is set up, scp works directly with aliases — no need to type out the full IP every time