Ponytail Lite is a stripped-down instruction file for coding agents. It keeps the anti-overengineering rules in one `AGENTS.md` instead of a plugin system, hooks, commands, or MCP setup.
Builders who want their coding agent to check for existing code, standard library support, and native features before adding anything new.
You can keep agent work focused on the smallest useful change instead of letting it drift into extra machinery.
You copy one `AGENTS.md` file into the instruction location your agent already uses.
The file tells the agent to check whether something already exists, whether the standard library covers it, and whether a one-line fix is enough.
The README maps the same instructions to paths for Claude Code, Codex, Cursor, Gemini CLI, Copilot, Windsurf, and others.
It deliberately avoids hooks, slash commands, MCP servers, and mode switching.
AGENTS.md
One file. No plugin. He would have wanted it this way.
"Ponytail Lite" is Ponytail without the plugin madness.
Not to be confused with Ponytail's lite mode. This is a separate one-file version.
Just copy AGENTS.md into the place your agent reads instructions. That's it. No plugin, hooks, commands, MCP, or mode switching.
Ponytail is a beautiful contradiction: an anti-overengineering tool delivered as a whole plugin ecosystem, with lifecycle hooks, slash commands, MCP, statuslines, adapter tests, and enough install paths to make a senior engineer stare silently at the wall.
Ponytail Lite is what a lazy senior dev would have expected:
AGENTS.md
Could you just copy AGENTS.md from Ponytail? Yes... But:
The AGENTS.md here is not a byte-for-byte copy. It is an opinionated cleanup of the original: same lazy senior dev idea, less plugin baggage, and guardrails rewritten for people who just want the file.
Copy AGENTS.md, or copy the same text into whatever your agent calls "project instructions" or "rules".
| Agent | Put the Ponytail Lite text here |
|---|---|
| Aider | Your project instructions / conventions file |
| Antigravity CLI | AGENTS.md or .agents/rules/ponytail.md |
| Claude Code | CLAUDE.md or project instructions |
| Cline | .clinerules/ponytail.md |
| CodeWhale | AGENTS.md |
| Codex | AGENTS.md or Settings > Personalization > Custom instructions |
| Cursor | .cursor/rules/ponytail.mdc |
| Devin CLI | Custom instructions / project instructions |
| Gemini CLI | AGENTS.md |
| GitHub Copilot | .github/copilot-instructions.md |
| GitHub Copilot CLI | AGENTS.md, .github/copilot-instructions.md, or ~/.copilot/copilot-instructions.md |
| Hermes Agent | Custom instructions / system prompt |
| Kiro | .kiro/steering/ponytail.md |
| OpenClaw | Custom skill / instruction file |
| OpenCode | AGENTS.md or OpenCode instructions |
| Pi agent | Custom instructions / system prompt |
| Swival | AGENTS.md or ~/.config/swival/AGENTS.md |
| Windsurf | .windsurf/rules/ponytail.md |
| Zed | Custom instructions / rules |
Delete the file you copied.
If you pasted the text into a global instructions file, delete that paragraph.
No leftover mode flag, statusline entry, and hidden MCP server still thinking about your dependency graph.
Before writing code, the agent climbs this ladder:
MIT
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