Overview

You already know skills from the Chat course. The way you build them, and the iterate-through-use pattern that gets them sharp, is the same in Cowork. What's different is what a skill can actually do. Instead of shaping how Claude responds inside a conversation, a Cowork skill can run an end-to-end workflow that touches your local files, your tools, and your connectors, all from a single prompt.

This chapter covers what that unlocks, how to build a good Cowork skill, and how plugins fit into the picture.

What Changes About Skills in Cowork

In Chat, a skill shapes how Claude responds inside a conversation. You're still in the loop for every step, and the skill effectively ends at the chat window.

In Cowork, a skill can span everything Cowork can reach: your local files, the tools on your computer, your connectors. A single prompt can trigger a workflow that reads a folder, builds an Excel file, drafts an email in your voice, and drops the draft into your Gmail ready to send. The whole thing happens in one run, without you stepping in between.

Skills in Cowork stop being "how Claude responds" and start being "what gets done, end to end."

How to Build One

The most important thing to know about building skills, whether in Chat or Cowork, is to not write them from scratch. If you sit down and try to document every step of a workflow in the abstract, the skill ends up brittle and generic. It's guessing at what you want rather than learning from what you actually did.

The approach that works is to do the task once in a real Cowork conversation, get it right through normal iteration, and then ask Cowork to capture the whole thing as a skill.

Here's what that looks like in practice. Imagine you're running a monthly review of meeting transcripts, and you've already got a task in Cowork that takes a folder of transcripts and produces a tracking spreadsheet, per-person summaries, and a team report. Now you want to extend it. You want a short email to leadership summarising the headlines, in the tone you'd actually use.

You'd go back into that existing task and ask for the extra piece:

"Now draft a short email to leadership summarising the key takeaways. Under 150 words, lead with what needs their attention, and attach the full report."

Cowork drafts the email using the report it already built. The content is right but maybe the tone reads too formal for how you'd actually write to that team. So you give it feedback:

"Too formal. Make it more direct and conversational, like I'm updating colleagues, not writing a board memo."

A revised version comes back, and now the workflow does what you want from start to finish. So you ask Cowork to capture it:

"Go back through our conversation and create a skill from this whole workflow."

Cowork writes the skill file. You save it, and the next time you run a review, the whole thing happens from a single prompt.

Updating a Skill

The first version of a skill is rarely the final one. You use it, notice what's missing, and refine. That iteration isn't a sign something went wrong; it's the point of the whole approach.

The way you update a skill in Cowork is the same as the way you built it: by asking. So if, after using the skill a few times, you decide you'd rather the email always called out overdue action items at the top, you tell Cowork:

"Update the skill so the email always includes a one-line summary of overdue action items at the top."

Cowork edits the skill file directly. You reinstall it, and the next run picks up the new version.

The same applies if you want to extend the skill to a new tool. You can take a skill that drafts an email as plain text in the chat and ask Cowork to deliver the output through Gmail instead. It uses the connector you've already got set up, writes the draft straight into your Gmail, and then with one more prompt you can ask it to bake that step into the skill itself. From then on, a single prompt takes a folder of files all the way through to a ready-to-send draft in your inbox.

This is the compound effect. Each round adds something small, and over weeks and months the skill becomes something that handles the work the way you do, without you having to think about it.

What a Plugin Is

A plugin is a bundle of skills and connectors, configured together for a specific role. Sales, marketing, finance, customer success, and so on. Install one and Cowork already knows how to handle that type of work without you needing to build the skills from scratch.

You'll find them in the Customise section, where you can browse plugins available to your organisation alongside ones built by Anthropic and its partners. Each plugin lists the skills it includes and the connectors it brings with it.

Once a plugin is installed, the skills inside it behave just like any other skill. Cowork picks them up automatically when you ask for something relevant, or you can invoke one yourself by typing

/

Plugins are a good starting point, particularly for general role-based work. They won't fit your specific way of working perfectly out of the box, but the same iteration loop applies: install one, use it on real tasks, and shape the skills inside it through use.

Pause Here

Pick a task you do regularly that produces a real deliverable. Run it once in a fresh Cowork task and refine the output until it's right. Then ask Cowork to turn the whole workflow into a skill.

Test it on a different example of the same kind of task. If something's not quite right, refine through conversation rather than by rewriting the skill file by hand.

While you're there, have a look at the plugin marketplace and see if there's one that fits your role. Install it and try it on something real. You'll quickly get a feel for what's useful out of the box and what you'd want to customise.

Key Takeaways

• Cowork skills can run end-to-end workflows. They span your local files, tools, and connectors, so a single prompt can take a job from raw inputs to a ready-to-send deliverable.

• Don't write skills from scratch. Do the task once in a real Cowork conversation, iterate until it's right, then ask Cowork to capture the workflow as a skill.

• Update skills the same way you built them. Tell Cowork what you want changed and it'll edit the skill file directly. No manual rewriting.

• Plugins bundle skills and connectors for a specific role. Install one to get a sensible starting point, then shape the skills inside it through use.

• Iteration is the point. A skill on day one is fine. After months of refinement, it does the work the way you do, without you having to think about it.