Codex CLI

opencodeCoding Agents

The distinguishing idea is that everything is declared rather than hard-wired: you define named agents in JSON or a markdown file, give each one its own model and its own per-tool permissions — allow, ask or deny for reading, editing and running commands — and switch between them with a keystroke. Two built-in primary agents ship this way, one with full access and one that asks before editing or running anything. It is MIT and provider-agnostic, but it moves fast and it recently changed hands, so old links and pinned versions go stale quickly.

PonytailCoding Agents

Ask an agent for a date picker and you can get a dependency, a wrapper component, a stylesheet and a conversation about time zones, when the browser has had `<input type="date">` for years. Ponytail is a single skill aimed at that habit: it pushes the agent towards the smallest thing that works, and towards not writing anything when the platform already provides it. What makes it worth a look rather than a joke is that the maintainers measured it — twelve real tasks on a real repository, with and without the skill — and published the method alongside the numbers, including a note that an earlier, more flattering figure was the per-task ceiling rather than the average.

gemini-cliCoding Agents

Google's own agent for the terminal: it reads a repository, edits files, runs shell commands, and can ground an answer in a live Google Search without extra setup. A read-only plan mode drafts the work before anything is written, a policy file settles in advance which tools may run, and one extension can install MCP servers, commands, subagents, skills and hooks together. It talks only to Gemini models, so it is a poor fit if you expect to switch providers or work offline — and since 18 June 2026 a personal Google sign-in no longer reaches it, leaving an API key, Vertex AI, or a Code Assist Standard or Enterprise licence.