diff --git a/AGENTS.md b/AGENTS.md
index 89d27a0..c53d9a5 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -17,6 +17,7 @@ Set up new or existing projects for AI coding agents in one command: AGENTS.md,
 Installed skills live in `.agents/skills/` (shared by Antigravity and Codex):
 - **Engineering**: the full stable Matt Pocock skill set — 27 skills covering `tdd`, `code-review`, `diagnosing-bugs`, `to-spec`, `to-tickets`, `implement-spec`, `pr`, `research`, `retro`, `triage`, and more (see `.agents/skills/`)
 - **Prose & Copy**: Use `humanizer` skill to eliminate AI writing tells and refine documentation.
+- **Simplicity**: Use `ponytail` skill for the smallest complete change and to cut over-engineering.
 - **Codebase Graph**: Use `graft ask "<query>" --source` or `graft map` for orientation before raw grep.
 
 ## Bootstrap & First Session
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d160775..0b7d022 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@
 
 ### Added
 
+- The [ponytail](https://github.com/DietrichGebert/ponytail) skill installs by default in every preset, and AGENTS.md points agents to it for the smallest complete change (#5). Existing configs keep their skill sources as written; add `dietrichgebert/ponytail` to `skills.sources` to opt in.
+
 - `aginit doctor` verifies the agent-browser runtime when the project ships the skill: CLI presence, upstream `agent-browser doctor --quick --offline --json` findings, and Chrome sandbox prerequisites.
 
 ## 0.2.0 — 2026-10-09
diff --git a/README.md b/README.md
index 913144d..955490f 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ aginit sets all of this up the same way every time, and you can re-run it whenev
 | | |
 |---|---|
 | **Instructions** | `AGENTS.md` with the project's real commands, invariants and a first-session playbook, shared by Antigravity, Codex and any agent that reads `AGENTS.md` |
-| **Skills** | All 27 stable [Matt Pocock skills](https://github.com/mattpocock/skills) (`tdd`, `code-review`, `diagnosing-bugs`, `to-spec`, `to-tickets`, `implement-spec`, `pr`...) plus [humanizer](https://github.com/blader/humanizer), installed in `.agents/skills/` via the [Skills CLI](https://github.com/vercel-labs/skills) |
+| **Skills** | All 27 stable [Matt Pocock skills](https://github.com/mattpocock/skills) (`tdd`, `code-review`, `diagnosing-bugs`, `to-spec`, `to-tickets`, `implement-spec`, `pr`...) plus [humanizer](https://github.com/blader/humanizer) and [ponytail](https://github.com/DietrichGebert/ponytail), installed in `.agents/skills/` via the [Skills CLI](https://github.com/vercel-labs/skills) |
 | **Codebase graph** | [Graft](https://www.npmjs.com/package/@nanonets/graft): `graft map` and `graft ask` give agents the relevant code spans before they grep |
 | **Test tooling** | Vitest for TypeScript projects, plus Playwright when a web framework is selected |
 | **Web extras** | [Impeccable](https://github.com/pbakaus/impeccable) for UI design and [agent-browser](https://github.com/vercel-labs/agent-browser) for visual QA, with its CLI and browser binaries installed so it works out of the box |
diff --git a/THIRD_PARTY_NOTICES.md b/THIRD_PARTY_NOTICES.md
index ed9ba65..a6bd34a 100644
--- a/THIRD_PARTY_NOTICES.md
+++ b/THIRD_PARTY_NOTICES.md
@@ -24,6 +24,12 @@ Each integrated upstream tool is governed by its respective authors and licenses
   - Author: Blake Robbins / Humanizer contributors
   - Repository: https://github.com/blader/humanizer
 
+- **Ponytail**
+  - Project: Agent skill for the smallest complete change and less over-engineering
+  - Author: Dietrich Gebert
+  - License: MIT
+  - Repository: https://github.com/DietrichGebert/ponytail
+
 - **Impeccable**
   - Project: Frontend craft & design system review skill
   - Author: Peter Bak-Hansen
diff --git a/aginit.config.json b/aginit.config.json
index 3093629..e35b61a 100644
--- a/aginit.config.json
+++ b/aginit.config.json
@@ -44,6 +44,10 @@
       {
         "package": "blader/humanizer",
         "skills": ["humanizer"]
+      },
+      {
+        "package": "dietrichgebert/ponytail",
+        "skills": ["ponytail"]
       }
     ]
   },
diff --git a/src/adapters/agents-md.ts b/src/adapters/agents-md.ts
index 5f23337..9598f24 100644
--- a/src/adapters/agents-md.ts
+++ b/src/adapters/agents-md.ts
@@ -62,6 +62,12 @@ export function generateAgentsMarkdown(
       '- **Prose & Copy**: Use `humanizer` skill to eliminate AI writing tells and refine documentation.';
   }
 
+  let simplicityCapability = '';
+  if (skillInstalled('ponytail')) {
+    simplicityCapability =
+      '- **Simplicity**: Use `ponytail` skill for the smallest complete change and to cut over-engineering.';
+  }
+
   let uiCapability = '';
   if (isWeb && skillInstalled('impeccable')) {
     uiCapability =
@@ -109,6 +115,7 @@ export function generateAgentsMarkdown(
       : 'Skills installation is disabled in this configuration.',
     engineeringCapability || undefined,
     proseCapability || undefined,
+    simplicityCapability || undefined,
     specCapability || undefined,
     uiCapability || undefined,
     browserCapability || undefined,
diff --git a/src/config/defaults.ts b/src/config/defaults.ts
index 440da7f..2875349 100644
--- a/src/config/defaults.ts
+++ b/src/config/defaults.ts
@@ -82,6 +82,10 @@ export function getDefaultConfig(
               package: 'blader/humanizer',
               skills: ['humanizer']
             },
+            {
+              package: 'dietrichgebert/ponytail',
+              skills: ['ponytail']
+            },
             {
               package: 'pbakaus/impeccable',
               skills: ['impeccable']
@@ -127,6 +131,10 @@ export function getDefaultConfig(
             {
               package: 'blader/humanizer',
               skills: ['humanizer']
+            },
+            {
+              package: 'dietrichgebert/ponytail',
+              skills: ['ponytail']
             }
           ]
         },
@@ -165,6 +173,10 @@ export function getDefaultConfig(
             {
               package: 'blader/humanizer',
               skills: ['humanizer']
+            },
+            {
+              package: 'dietrichgebert/ponytail',
+              skills: ['ponytail']
             }
           ]
         },
diff --git a/tests/agents-md.test.ts b/tests/agents-md.test.ts
index 51785e7..39db4a4 100644
--- a/tests/agents-md.test.ts
+++ b/tests/agents-md.test.ts
@@ -29,6 +29,16 @@ describe('AGENTS.md generation & safety', () => {
     expect(md).toContain('Prose & Copy');
   });
 
+  it('includes ponytail guidance only when the ponytail skill is configured', () => {
+    const config = getDefaultConfig('demo-generic', 'generic');
+    expect(generateAgentsMarkdown(config)).toContain('`ponytail`');
+
+    config.skills.sources = config.skills.sources.filter(
+      (s) => s.package !== 'dietrichgebert/ponytail'
+    );
+    expect(generateAgentsMarkdown(config)).not.toContain('ponytail');
+  });
+
   it('reflects selected package manager in Essential Commands', () => {
     const configNpm = getDefaultConfig('demo-npm', 'web', { framework: 'vite', packageManager: 'npm' });
     const mdNpm = generateAgentsMarkdown(configNpm);
diff --git a/tests/config.test.ts b/tests/config.test.ts
index 90a698b..3638c1b 100644
--- a/tests/config.test.ts
+++ b/tests/config.test.ts
@@ -32,6 +32,14 @@ describe('Configuration & Defaults', () => {
     expect(packages).toContain('vercel-labs/agent-browser');
   });
 
+  it('installs the core ponytail skill in every preset', () => {
+    for (const preset of ['web', 'cli', 'generic'] as const) {
+      const config = getDefaultConfig('app', preset);
+      const ponytail = config.skills.sources.find((s) => s.package === 'dietrichgebert/ponytail');
+      expect(ponytail?.skills).toEqual(['ponytail']);
+    }
+  });
+
   it('supports explicit packageManager choices: npm, yarn, bun', () => {
     const configNpm = getDefaultConfig('app-npm', 'web', { packageManager: 'npm' });
     expect(configNpm.packageManager).toBe('npm');