Open sourceJavaScript · ≈180k stars · MIT

Ponytail

Name: Ponytail
Author: DietrichGebert

A minimalism skill: your agent thinks like the laziest senior dev in the room.

DietrichGebert/ponytail

Maintained by DietrichGebert

Coding Agents

Ponytail is one prompt, a SKILL.md with a compact AGENTS.md version, that pushes coding agents to write less code. It installs as a Claude Code plugin or a Codex plugin with two lifecycle hooks, and any agent that reads a rules file can use it.

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Pros & cons

Each point cites its sources and says what kind of evidence backs it. A second reviewer tried to refute every claim before it was kept.

Pros

DocsThe author's benchmark (39 tasks, Opus 5.5, 5 runs each) reports 53% less code, 45% fewer tokens and 26% lower cost, with all 30 runs of the six security tasks passing.[1]
DocsIts stated rule is to never cut validation, error handling, security or accessibility, and it reports 98% of risky logic shipping with a test, against 68% without it.[1]
DocsVersion 5.3 added a Claude Code band that shows cost, tokens and per-turn spend.[1]
User reportsOne commenter finds its basic simplicity heuristics useful for getting agents to make quick, small edits.[1]

Cons

DocsAll headline numbers come from the author's own benchmark rather than independent replication.[1]
User reportsSkeptics say it is a handful of rules plus a lot of plugin boilerplate, replaceable by asking 'Is there a simpler solution?'[1][2]
User reportsUsers asked for measurements on standard benchmarks (SWE-Bench Pro, Terminal Bench) and objected to it adding 'ponytail:' markers to code comments and commit messages.[1][2]
User reportsHarness drift: the OpenCode plugin used a V1-only API and did nothing on OpenCode 2 (September 2026, closed).[1]

Best for: Teams fighting agent over-engineering who want smaller diffs without dropping safety checks.
Watch out for: Check the claimed savings on your own repo before relying on them.

Assessed Oct 29, 2026 · adversarially reviewedSuggest a correction

MDX · ≈307k stars · MIT