# Claude Cowork plugins and skills: what they are and how to install one · Stacktree

Source: https://stacktr.ee/claude-cowork-plugins

[Skip to content](#main)   [stacktr.ee](/)  [Examples](/#proof) [How it works](/#how) [Pricing](/pricing) [Security](/security) [Log in](https://app.stacktr.ee) [Publish one](https://app.stacktr.ee/?join=1)     By [Steve Smith](/about) · Founder, Stacktree Last updated September 20, 2026          for Claude Cowork

#  Claude Cowork plugins and skills

   One install, and Claude has a workflow it did not have before.  A plugin package can declare skills, MCP connectors, subagents and hooks in a single manifest. Here is what the format contains, how to install one from the catalogue or from any Git repository, the 43 workflows in Claude for Small Business, and the Stacktree publish plugin.

     install npx skills@latest add stevysmith/stacktree-skill
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  [ Get started free ](https://app.stacktr.ee/?join=1&from=seo_claude_cowork_plugins)   No card. 3 free pages, each live for 7 days.

##  What is a Claude Cowork plugin?

A Cowork plugin is a package that extends what Claude can do. One manifest can declare skills,
      MCP connectors, subagents and hooks, and installing it adds all of them at once. Plugins come
      from Anthropic's catalogue, from your organisation, from any Git repository you add as a
      marketplace, or from a package file you upload yourself.

## What a plugin can contain

The manifest declares any combination of four component types, and Anthropic documents them
      plainly:

  - Skills. Reusable instructions that teach Claude a workflow.
 - Connectors. MCP servers that give Claude access to an external service.
 - Agents. Specialised subagents Claude can delegate to.
 - Hooks. Scripts that run at defined points in a session.

Installing a plugin installs all of them together, which is the whole reason the format exists.
      A workflow is rarely just an instruction: it needs the connector that reaches the accounting
      system, the subagent that handles the fiddly sub-job, and sometimes a hook that fires when a
      session starts. Once installed, the skills and agents appear as tabs on the plugin, while
      connectors and hooks get their own pages, and you can enable or disable each piece.

Plugins run in Cowork and in Claude Code, and are not used in chat. Skills are the part that
      travels: a skill that arrives through a plugin becomes available in chat as well.

## How to install one

  - Open Customize in the sidebar, then Plugins.
 - Select Browse plugins. The default marketplace is Anthropic's official catalogue, and you can add others by URL.
 - Select a plugin and click Install. If it ships a connector that needs authentication, you are prompted to sign in.
 - Open the installed plugin to review its skills, connectors, agents and hooks, and turn individual components off if you do not want them.

Two other routes exist. To install something that is not in a catalogue at all, use the upload
      option on the Plugins page and select the plugin package. To follow a repository, choose
Add marketplace and paste its URL: Cowork takes the standard
`https://github.com/owner/repo` form and the `owner/repo` shorthand, and
      public GitLab and Bitbucket repositories work too. Click Update on a
      marketplace to pull its latest plugins.

On Team and Enterprise plans, administrators can require plugins for everyone. Those install
      automatically, say so on the plugin, and cannot be removed by the person using them.

## The limits, before you package something large

The published defaults are 200 MB uncompressed per plugin package, 5,000 files per package, a
      512 MB marketplace repository archive, 500 plugins per marketplace, and 25 marketplaces per
      person. The in-app skill viewer previews files up to 1 MB and shows larger ones as too large to
      preview, though Claude can still read them at runtime.

## Claude for Small Business: the flagship plugin

The clearest example of what a Cowork plugin is for arrived on 15 September 2026. Claude for
      Small Business is Anthropic's own plugin, it runs in Cowork, and it ships 43 ready-to-run
      workflows aimed at the operating rhythm of a company rather than at a codebase. It connects to
      37 eligible partner services, including QuickBooks, PayPal, HubSpot, Shopify, Salesforce,
      Stripe, Xero, Square, Gusto, Canva, DocuSign, Google Workspace, Microsoft 365, Slack and
      Zapier, and where a connector does not exist it works from spreadsheets and statements. It is
      available on every paid Claude plan, with Team recommended for businesses with more than one
      user.

 The named workflows give the shape of it:

  - SMB onboard. The setup run: connect your tools and pick the first tasks.
 - Monday brief. Cash position, last week's sales against the week before, what moved in the pipeline, which invoices are overdue, on one page.
 - Speed to lead. Qualifies an inbound enquiry, drafts the reply with real calendar availability, and logs it to the CRM.
 - Proposal builder. Turns a voice memo, a photo or an RFP into a branded proposal, priced from your past jobs.
 - Social content engine. Drafts posts in your voice with on-brand graphics, cut into every format your channels need.
 - Close month. Reconciles the books against the payment processors, flags mismatches down to the transaction, and writes a plain-English profit and loss.

Beyond those six the catalogue continues: Plan payroll, Pay the bills, Restock, Tax prep, Grow
      pipeline, Call list, Marketing Monday, plus two meta-workflows, one that builds a connector for
      an unsupported tool through Zapier and one that turns a manual weekly task into a schedulable
      workflow of your own.

The constraint Anthropic repeats is the important one. The skills draft, propose and stage; you
      approve before anything sends, posts or pays. Workflows begin in approval mode, and automating
      one is a decision you make afterwards.

## The gap at the end of Proposal builder

Read that workflow list again and notice where every one of them stops. Proposal builder ends
      with a priced, branded proposal in a folder. Monday brief ends with a page you could show
      somebody. Close month ends with a profit and loss your accountant needs. None of them ends with
      the thing reaching a person outside your company, because sending is deliberately the part that
      waits for you.

Which leaves the oldest bad habit in professional services: attach it to an email. The client
      downloads a file, opens it from their file system, and you never learn whether it was read. For
      a proposal, which is a document whose entire job is to be opened and acted on, that is the
      worst possible last mile.

## The Stacktree plugin

Stacktree publishes an HTML page to a private, unguessable URL that opens in any browser with
      no account for the viewer, with an optional passcode or company email gate, an expiry, a read
      receipt, and replace-in-place so a link you already sent never goes stale.

It ships as a plugin package in the open at
[github.com/stevysmith/stacktree-skill](https://github.com/stevysmith/stacktree-skill),
      in the standard format: `.claude-plugin/plugin.json` declares the plugin and
`.claude-plugin/marketplace.json` makes the repository itself a marketplace. Inside
      are the publish skill, the job-shaped skills for client deliverables, agent run reports, daily
      briefs and status dashboards, and the Stacktree MCP server. Because Cowork accepts a Git
      repository as a marketplace, that repository URL can be added on the Plugins page directly. It
      is not listed in Anthropic's own catalogue, and this page will say so until it is.

For agents that read the open skills index instead, the same skill installs with
`npx skills@latest add stevysmith/stacktree-skill`, and every MCP client can reach
      the hosted server at `https://api.stacktr.ee/mcp` over OAuth. The verb list is on
[the MCP publish tool](/mcp-publish-html), and the Claude Code side is on
[publish HTML from Claude Code](/claude-code).

FAQ

## Frequent questions

     What are Claude Cowork plugins? +  A plugin is a package that extends what Claude can do in Cowork. One manifest can declare any combination of skills, MCP connectors, subagents and hooks, and installing it adds all of them in a single step. After installing, the plugin’s skills and agents appear as tabs, while connectors and hooks get their own pages so you can enable or disable each piece.   What is the difference between a skill and a plugin in Claude? +  A skill is one set of reusable instructions that teaches Claude a workflow. A plugin is the package that ships skills together with the other things a workflow needs: the MCP connectors that reach an outside service, the subagents Claude can delegate to, and the hooks that run at defined points in a session. You can install a single skill on its own, or a plugin that brings several skills and their plumbing at once.   How do I install a plugin in Claude Cowork? +  Open Customize in the sidebar, then Plugins. Select Browse plugins to see the catalogue, pick one, and click Install. If the plugin includes a connector that needs authentication you are prompted to sign in. To install something that is not in the catalogue, either add its Git repository as a marketplace or use the upload option on the Plugins page and select the plugin package.   Do plugins work in Claude chat? +  No. Anthropic’s documentation states that plugins are available in Cowork and Code and are not used in chat. Skills that arrive through a plugin do become available in chat, but the plugin itself is a Cowork and Claude Code concept.   What is the Claude for Small Business plugin? +  It is Anthropic’s own plugin for running a business, and it runs in Cowork. The 15 September 2026 launch post describes 43 ready-to-run workflows and 37 eligible partner integrations including QuickBooks, PayPal, HubSpot, Shopify, Salesforce, Stripe, Xero, Square, Gusto, Canva, DocuSign, Google Workspace, Microsoft 365, Slack and Zapier. It is available on every paid Claude plan, with Team recommended for businesses with multiple users.   What workflows does the Small Business plugin include? +  The named ones include SMB onboard to connect your tools, Monday brief for cash, sales, pipeline and overdue invoices on one page, Speed to lead to qualify an inbound enquiry and reply with real meeting times, Proposal builder to turn a voice memo, photo or RFP into a branded proposal priced from your past jobs, Social content engine to draft posts in your voice with on-brand graphics, Close month to reconcile the books and write a plain-English profit and loss, plus Plan payroll, Pay the bills, Restock, Tax prep, Grow pipeline, Call list and Marketing Monday.   Does the Small Business plugin send things without asking? +  No. Anthropic is explicit that the skills draft, propose and stage, and that you approve before anything sends, posts or pays. Workflows start in approval mode before you choose to automate them. Cowork’s own approval modes sit underneath that: manual asks on every action, auto runs continuously with safety checks that block unsafe steps, and skip asks for nothing.   Can I add my own plugin marketplace to Claude Cowork? +  Yes. Any Git repository that contains plugin packages can act as a marketplace, which is the usual way a team distributes its own plugins without publishing to the public catalogue. On the Plugins page choose Add marketplace and paste the repository URL. GitHub, including GitHub Enterprise, is supported, and public repositories on GitLab and Bitbucket work too. Click Update on a marketplace to pull its latest plugins.   Are there limits on Cowork plugin size? +  Yes, and they are generous. The published defaults are 200 MB uncompressed per plugin package, 5,000 files per package, a 512 MB marketplace repository archive, 500 plugins per marketplace, and 25 marketplaces you can add. The in-app skill viewer previews individual files up to 1 MB; larger files are still available to Claude at runtime.   Is there a Stacktree plugin for Claude Cowork? +  There is a Stacktree plugin package, published in the open at github.com/stevysmith/stacktree-skill. It carries the standard manifest pair, .claude-plugin/plugin.json and .claude-plugin/marketplace.json, and ships the publish skill, the job-shaped skills for client deliverables and reports, and the Stacktree MCP server. Because Cowork can take a Git repository as a marketplace, that repository URL is installable directly. It is not listed in Anthropic’s own catalogue.
Keep reading

## Related guides

   -  [ What is Claude Cowork? Plans, platforms, use cases, and how it differs from Claude chat. ](/what-is-claude-cowork)
-  [ Claude Cowork vs Claude Code Same agentic engine, two front doors. Which one your work belongs in. ](/claude-cowork-vs-claude-code)
-  [ Send Cowork output to a client The step after Proposal builder: a private link, a passcode, a read receipt. ](/share-claude-cowork-output-with-client)
-  [ Publish HTML from Claude Code One command, one OAuth sign-in, a private link in a tool call. ](/claude-code)
-  [ Share a Claude Design privately The export-then-publish move for design files. ](/share-claude-designs)
-  [ npx skills, explained The open skills CLI, what the commands do and where files land. ](/skills)

References

## Sources and further reading

   -  [ Claude Docs: install plugins ↗ The component table, the install steps, the Git marketplace mechanics and the package limits quoted here. ](https://claude.com/docs/cowork/guide/plugins)
-  [ Anthropic: Claude for Small Business ↗ The 15 September 2026 launch post: 43 workflows in Cowork, the named ones, and the integration list. ](https://claude.com/blog/claude-for-small-business-launches-new-workflows-integrations-and-training-programs)
-  [ Claude Help Center: browse skills, connectors and plugins ↗ How the one directory distinguishes skills, connectors and plugins, and where installed skills show up. ](https://support.claude.com/en/articles/14328846-browse-skills-connectors-and-plugins-in-one-directory)
-  [ GitHub: stacktree-skill ↗ The Stacktree plugin package and marketplace manifest, in the open. ](https://github.com/stevysmith/stacktree-skill)

##  Add the last step the workflow does not have.

 Proposal built, report written, month closed. Publish it to a private link the client opens in a browser, with no account.

 [ Sign up free → ](https://app.stacktr.ee/?join=1&from=cta_claude_cowork_plugins)   install npx skills@latest add stevysmith/stacktree-skill
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