Marketing Skills Turns Your Coding Agent into a CRO Consultant

What it does

Marketing Skills is a collection of markdown files that give AI coding agents (Claude Code, Codex, Cursor, Windsurf) specialized marketing knowledge. 35 skills covering CRO, copywriting, SEO, cold email, pricing, churn prevention, and more. 19k+ stars.

Why I starred it

Most "AI prompt collections" are surface-level. This one is different because the skills aren't prompts — they're structured instruction sets that follow the Agent Skills spec. Each skill turns your coding agent into a domain expert for a specific marketing task. Ask it to optimize a landing page and it runs a full CRO analysis framework. Ask it to write a cold email sequence and it applies actual copywriting methodology.

The practical angle is what caught my eye. I spend time building sites and landing pages. Having an agent that can apply a structured CRO framework to a page I just built — without context-switching to a different tool — is genuinely useful.

How it works

The architecture is intentionally simple. Each skill lives in skills/<name>/SKILL.md with YAML frontmatter:

---
name: page-cro
description: When the user wants to optimize conversions on any marketing page...
metadata:
  version: 1.1.0
---

The description field doubles as a trigger — agents use it to decide when to activate the skill. The page-cro skill, for example, lists phrases like "this page isn't converting," "bounce rate is too high," and even "this page needs work" so the agent picks it up from natural language.

The real substance is in the skill bodies. Take skills/page-cro/SKILL.md — it's not a vague prompt. It defines a multi-dimensional CRO analysis framework: value proposition clarity, headline effectiveness, CTA hierarchy, social proof placement, objection handling, and page structure. Each dimension has specific checks, common issues, and strong/weak examples.

What I appreciate is the dependency graph. Skills reference each other explicitly. The product-marketing-context skill acts as a shared foundation — every other skill checks for .agents/product-marketing-context.md first to understand your product, audience, and positioning before doing anything. The README has a full dependency diagram showing how copywriting links to page-cro links to ab-test-setup.

Skills can also pull in reference material from subdirectories:

skills/cold-email/
├── SKILL.md
└── references/
    ├── benchmarks.md
    ├── follow-up-sequences.md
    ├── frameworks.md
    ├── personalization.md
    └── subject-lines.md

This keeps the main SKILL.md under 500 lines while offloading detailed data to files that get loaded on demand.

Beyond skills, there's a tools/clis/ directory with 61 zero-dependency Node.js CLI wrappers for marketing APIs — GA4, Ahrefs, Stripe, HubSpot, Mailchimp, and dozens more. Each one follows the same pattern: env var for auth, parseArgs() for CLI flags, and a --dry-run mode that previews the API request without sending it. Looking at tools/clis/ga4.js, the argument parser is hand-rolled in about 15 lines — no dependencies, just process.argv slicing. Every tool outputs JSON, making them composable with agents.

The CI pipeline in .github/workflows/validate-skill.yml is clean. It detects which SKILL.md files changed, builds a matrix of affected skills, and runs each through Flash-Brew-Digital/validate-skill@v1 to enforce the spec constraints (name format, description length, frontmatter validity). The sync-skills.js script in .github/scripts/ keeps the README's skills table and the .claude-plugin/marketplace.json manifest in sync automatically.

Using it

Install with the skills CLI:

# Install all 35 skills
npx skills add coreyhaines31/marketingskills

# Or pick what you need
npx skills add coreyhaines31/marketingskills --skill page-cro copywriting cold-email

Then just talk to your agent naturally:

"Help me optimize this landing page for conversions"
→ Uses page-cro skill

"Write a 5-email welcome sequence for new trial users"
→ Uses email-sequence skill

For Claude Code specifically, there's a plugin install path:

/plugin marketplace add coreyhaines31/marketingskills
/plugin install marketing-skills

Rough edges

The skills are content-only — no tests for the skill content itself. The CI validates structure (frontmatter format, name conventions) but not whether the advice is any good. That's a reasonable tradeoff for a content repo, but it means quality depends entirely on the maintainer's marketing expertise.

The 61 CLI tools in tools/clis/ are useful but feel bolted on. They're not referenced by the skills themselves in any structured way — the connection between "use the analytics-tracking skill" and "here's a GA4 CLI tool" is documented in REGISTRY.md but not enforced. You have to know to look.

There's no versioning per skill beyond the optional metadata.version field. The VERSIONS.md approach works for checking updates, but there's no lockfile or pinning mechanism. If a skill changes in a way that breaks your workflow, you'll find out at runtime.

The product-marketing-context dependency is smart in theory — every skill reads your product context first. In practice, if you haven't created that file, each skill falls back to asking you questions. That's fine the first time. By the third skill invocation asking "what's your product?", you'll want to write that context file.

Bottom line

If you're a technical founder or developer who builds landing pages, writes marketing copy, or runs growth experiments alongside your code — this turns your coding agent into a surprisingly competent marketing co-pilot. The skills are well-structured and the advice is specific enough to be actionable.