TermdockWhat Are AI CLI Tools and Why Do They Matter?
AI CLIs let you give tasks from a terminal and, depending on tool and permission settings, read projects, run commands, or edit files. They can fit into Git and testing workflows, but do not guarantee correct output or replace review. GUI editors also support agents; choose the surface that fits the work.
Ten AI CLI Tools to Know in 2026
| Tool | What to check first |
|---|---|
| Claude Code | Anthropic's CLI: subscription or API access and permission mode |
| Codex CLI | OpenAI's CLI: distinguish local work, cloud features, and account eligibility |
| GitHub Copilot CLI | GitHub workflows; organization users should check that policy enables it |
| Gemini CLI | Google's open-source CLI: verify account and API access |
| aider, Goose, Crush, OpenCode | Select a model or provider according to each tool's docs; an open-source client does not make model use free |
| Amp, Cline CLI | Check current service plans, authentication, and terminal workflows |
Google personal-account notice: Google's May 2026 announcement says Gemini CLI stopped serving Gemini Code Assist individual free and Google AI Pro/Ultra users on June 18, directing them to Antigravity CLI. Code Assist Standard/Enterprise and paid API paths remain supported. Its authentication and quota docs still list personal accounts and free quotas. The official sources conflict. Check the latest information and your own account; we have not tested every account type and do not treat the old 1,000 daily requests as a guarantee.
Your First AI CLI Task
- Select a CLI you can access. Install and authenticate from its official docs; check the plan, usage limit, and data policy.
- Open a project you are authorized to use. Check the working directory and Git state, and protect important unsaved data first.
- Start with a read-only question such as: "List the main entry points and test commands with file paths; do not edit." Use the tool's actual permission controls: a prompt alone is not isolation.
- Verify the answer, then request a small change. Ask for the diff, tests run, and actual output.
- Inspect the changes and test results before deciding whether to commit or deploy. If installation, access, or usage fails, do not assume the tool is ready.
The Dual-Tool Strategy: Explore, Implement, Review
One session can inspect the current state, another implement, and an independent session check the requirement against the diff. Pass the task, relevant paths, permitted actions, and expected output explicitly: conversations do not share context automatically. Two sessions are not necessarily faster or cheaper; measure cost and quality on your own tasks.
In a Termdock project workspace, you can open terminals and hand off manually. For an agent-driven Claude Code-to-Codex review on macOS, install the termdock CLI and bundled terminal skill, then ask Claude Code to open an installed, authenticated Codex, send the requirement and diff location, and read its read-only review. Verify findings, changes, and tests before deciding what to do. Windows supports the desktop and HTTP Terminal API; one-click CLI installation is macOS-only. See the Claude Code and Codex handoff walkthrough.
Context Engineering: CLAUDE.md, AGENTS.md, and Beyond
Put architecture, verification commands, and constraints in files each tool actually reads. Claude Code's CLAUDE.md and Codex's AGENTS.md are not automatically loaded by every tool; consult their docs. Install task-specific skills in each supported location and format. Test a concrete task to see which instructions are read; an open workspace does not prove all settings loaded.
See the CLAUDE.md writing guide and skill comparison for examples.
Multi-Agent Development with Git Worktree
When agents need to edit in parallel, create separate worktrees and branches using the Git documentation. This example assumes the repository already has a commit and both names and destination paths are unused:
git worktree add -b feature/auth ../project-auth HEAD
git worktree add -b feature/api ../project-api HEAD
Enter the corresponding directory in each terminal and assign tasks and file ownership. Ask each agent for its branch, diff, tests, and open items. Inspect conflicts and dependencies before deciding whether to merge. Worktrees separate working directories but share the Git repository; they are not a permission sandbox. Termdock recognizes existing worktrees but does not automatically create one for every agent.
Cost Reality Check: What You Will Actually Spend
Subscriptions, API tokens, models, cloud environments, and external services can be billed separately. An open-source CLI may use a paid model. Check provider plans and usage pages, then compare total costs over a representative period. Prices and quotas change; do not assume a fixed savings percentage or request allowance.
The free AI CLI comparison explains free clients, account quotas, and local-model costs. Verify current plans before use.
Terminal Emulators for AI CLI: Ghostty, Warp, and the Rest
Many terminals can run a single CLI. Multiple long-running tasks also require clear working directories, processes, and output. Termdock provides desktop workspaces on macOS and Windows, plus terminal handoffs, connected computers, and phone-browser operation. Phone access needs pairing and a reachable host; it is not the full desktop app. The terminal multiplexing comparison covers tmux, Zellij, and Termdock lifecycles and limits.
MCP and ACP: The Protocol Layer
MCP connects compatible agents to tools, data, and services; ACP addresses interactions between agents and clients. Before connecting an MCP server, check its source, available operations, and data permissions. Do not put production credentials in examples or prompts. Verify with test data before granting more access. See Build Your First MCP Server for setup and troubleshooting.
Security: Supply Chain Attacks and Permission Models
Check sources and versions before installing a CLI, skill, or MCP server, and inspect its dependencies and scripts. Grant only the file, network, and service permissions needed; check the agent's actual sandbox and approval configuration. Git worktrees, separate terminals, and different workspaces are not security isolation. Check provider policies for sensitive data and keep readable backups of important files.
Getting Started Checklist
Choose an accessible CLI and complete one verifiable small task. Once comfortable, add a second session for read-only review; create worktrees when parallel edits actually require them. Record real tests, costs, and unresolved questions before expanding the workflow.