AGENT SKILLS

Agent skills

Find a workflow for SEO, AEO, Paid Ads, CRO or Content. Compare its inputs, output, author and account access, then install the skill that fits your task. Open-source skills for Claude Code, Cursor and Codex, on five shelves, plus Addition’s own packs.

Skills
30
Libraries
6
Run with no key
28
Toolkits
6
Updated
11 Sept 2026

Getting started

New to skills? Two short pages cover what one is and how it gets into your agent.

Browse by channel

Five shelves and the toolkits. Each shelf page says what its skills do together and what they cannot replace.

All 30 skills, shelf by shelf

Every page has the same blocks: the install command, what the skill needs, a four-row safety review, the phrases that trigger it, what is inside, one real run in full, and where the method differs.

SEO 7 skills

Packs by Addition

AEO and GEO 5 skills

Paid Ads 8 skills

Packs by Addition

CRO 5 skills

Content 5 skills

The question people ask

Are Claude skills useful?

Yes

For the part of the work that is reading, structuring and checking. Run on a live site, the audit skills on these shelves found a navigation that exists only after JavaScript runs, hero images at a megabyte each, a broken link in a mobile menu, and a product page whose copy describes a different product from its photos. None of that needed a key.

No

For the part that is measurement. No skill can see rankings, field Core Web Vitals, ad-account data or AI citations without a connection, and the better ones say so in their own text. The four RampStack skills carry an explicit rule that a stated gap is a complete answer and a fabricated number never is; the six claude-seo skills tell the agent not to guess site content when a fetch fails.

With defects

A sample-size table that disagrees with its reference file by about 2.5x, a crawler list that conflates OpenAI’s training bot with its search bot, a schema skill that still lists rich results Google retired. Each item page names them.

Questions

Questions people ask before installing

Do these work on the free version of Claude?

Skills are a Claude Code and Claude.ai feature; Claude Code needs a subscription or API access, and Claude.ai custom skills depend on your plan. The skills themselves are free, MIT or Apache-2.0 licensed files.

Do they work in Cursor or Codex?

The ones installed with npx skills add land in the folder each agent reads. The claude-seo plugin and its sub-skills are Claude Code only because they call plugin scripts.

What is the difference between a skill and an MCP server?

A skill is instructions the agent reads when a task matches; an MCP server is a program that gives the agent tools, such as reading your GA4 property. Skills tell it how; toolkits let it reach.

How do I install one?

For twenty of the twenty-five: npx skills add addition-labs/skills --skill name, from this shelf’s own repository. For the five claude-seo skills: the plugin install on the item page. The install page walks through both and the manual copy.

Are they safe?

Each page carries a four-row safety review of the SKILL.md and every script in its folder: network, shell, secrets, deletes. None of the 25 deletes user files; five call plugin scripts that fetch the web; one edits your codebase if you let it.