CLI Is the Best Harness for Coding Agents

🤔 Curiosity: Why does the CLI keep winning?

As coding agents handle longer‑horizon tasks, the terminal keeps emerging as the best harness to run, control, and scale them. The CLI is the place where code, shell, git, and automation already live—and that native proximity changes everything.

This post consolidates the linked tools and highlights what each CLI gets right.

📚 Retrieve: What each CLI agent actually ships

🥇 Gemini CLI (Google)

• Open‑source CLI agent with a free tier (60 req/min, 1,000 req/day)
• Gemini 3 models with 1M‑token context
• Built‑in tools: search grounding, file ops, shell commands, web fetching
• Extensible via MCP servers
• Install via npx/npm/brew

Repo: https://github.com/google-gemini/gemini-cli

🥈 OpenCode (Anomaly)

• Provider‑agnostic open‑source coding agent
• TUI‑first UX, client/server architecture, built by terminal‑first teams
• Built‑in agents (build/plan), optional subagent for deep search
• Cross‑platform installers + desktop app

Repo: https://github.com/anomalyco/opencode

🥉 Claude Code (Anthropic)

• Terminal‑native agent that understands your codebase and git workflow
• Works in terminal/IDE and can be tagged on GitHub
• Plugins system for extended commands and agents

Repo: https://github.com/anthropics/claude-code

Codex CLI (OpenAI)

• Lightweight local‑first CLI agent
• Simple install via npm/brew or binaries
• Works with ChatGPT sign‑in or API key

Repo: https://github.com/openai/codex

Qwen Code (Alibaba)

• Open‑source terminal agent optimized for Qwen3‑Coder
• OAuth free tier (2,000 req/day) or OpenAI‑compatible API
• Headless mode, IDE integrations, TypeScript SDK

Repo: https://github.com/QwenLM/qwen-code

Copilot CLI (Microsoft / GitHub)

• Terminal harness connected to repos, issues, PRs
• MCP‑powered extensibility + explicit approval for actions
• Requires Copilot subscription

Repo: https://github.com/github/copilot-cli

Kimi CLI (Moonshot)

• Terminal agent with built‑in shell mode (Ctrl‑X)
• MCP support + ACP IDE integration
• Zsh plugin + VS Code extension

Repo: https://github.com/MoonshotAI/kimi-cli

Mistral Vibe (Mistral)

• Minimal CLI coding assistant
• Built‑in agents, tool approvals, subagents
• Highly configurable; UNIX‑first support

Repo: https://github.com/mistralai/mistral-vibe

💡 Innovation: How I’d choose a CLI agent for real production

1) When I need maximum model context

Gemini CLI is the clear winner if I want long‑context reasoning and can stay inside Google’s ecosystem.

2) When I need provider freedom

OpenCode and Qwen Code keep the model layer flexible, which matters if I’m iterating on cost/latency trade‑offs.

3) When I need GitHub‑native workflows

Copilot CLI’s tight integration with issues/PRs is the strongest if the repo lives on GitHub and governance matters.

4) When I need a minimal but safe terminal agent

Mistral Vibe’s approval flow + subagents is a clean baseline for teams who want control.

Key Takeaways

Insight	Implication	Next Steps
CLI is the agent’s natural habitat	Lowest‑friction control loop	Standardize a CLI workflow
Provider lock‑in is a real tax	Open agents keep options open	Separate harness vs model
GitHub‑native flow accelerates shipping	Issues/PRs become part of the loop	Adopt Copilot CLI for repos

New Questions

• Which CLI agent becomes the default shell for teams?
• Do we need a single harness, or a portfolio of agents per task?
• What’s the right balance between automation and approval gates?

References

• https://github.com/google-gemini/gemini-cli
• https://github.com/anomalyco/opencode
• https://github.com/anthropics/claude-code
• https://github.com/openai/codex
• https://github.com/QwenLM/qwen-code
• https://github.com/github/copilot-cli
• https://github.com/MoonshotAI/kimi-cli
• https://github.com/mistralai/mistral-vibe