Out of the box, Cowork is powerful. Its real superpower is extensibility — but there are three mechanisms that sound alike and trip everyone up at first. Plugins bundle features. Skills make real files. MCP connectors reach external services. Once you can tell them apart, you'll know exactly what to install for any new capability — and when it's worth building your own.
Step 1 of 50% complete
The mental model
Three extension types, three jobs
These three get confused because they all "add capabilities." But each does it in a distinct way, and you'll use all three.
Skillmakes a file
A file-format expert. docx builds real Word docs, xlsx builds Excel, pptx builds decks. Skills are how Cowork produces actual files instead of chat text.
MCP connectorreaches a service
A bridge to something outside your local files. Outlook MCP reaches your M365 email, Slack MCP reaches Slack, Salesforce MCP reaches your CRM.
Pluginbundles both
A box of stuff for one job. A "Sales" plugin might bundle the Outlook connector + a follow-up-email Skill + prospecting prompts. Install one, get the whole workflow.
Remember it as: Skills make files. MCP reaches services. Plugins bundle both.
Predict first
You want Cowork to read and post in your team's Slack. Which extension type does the actual connecting?
Do it · sort them
Plugin, Skill, or MCP?
Six things you might install. Tag each one. If you can do this cleanly, the whole extension model is yours.
How to extend
Browse first, build last
The order matters. Most capabilities already exist — so check the marketplace before you write anything custom.
Install a plugin from the marketplace
Search by your role — Sales, Engineering, Marketing, Finance, Legal.
Check what MCP connectors it requires (some need OAuth).
Check what Skills it adds, and read the reviews — ratings flag the flaky ones.
Add a new MCP server for a service Cowork doesn't know
Search the MCP registry for the service (e.g. "Notion MCP server").
Check the publisher and last-updated date — pick maintained ones.
Add the install line to your config, restart, run OAuth if needed.
Test: "list my [service] resources."
Worth knowing: Slack, Notion, Linear/Jira/Asana, GitHub, HubSpot/Salesforce, Stripe, Postgres/Snowflake all have MCP servers.
Treat plugin installs like browser extensions. One from an unknown publisher can request broad permissions — only install from publishers you trust or with high ratings.
Do it · smart or risky?
Six calls about extending safely
Extensibility is power, and power needs judgment. For each move, decide: smart, or risky?
Call 1 of 6 · 0 right
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Lesson complete
You can extend Cowork without bloating or breaking it
What you can do now
Tell a Plugin, a Skill, and an MCP connector apart on sight
Search the marketplace before building anything custom
Vet plugins like browser extensions — publisher and ratings first
Use read-only credentials for any production system
Build a custom Skill only for workflows you'll run 5+ times
Your move: audit your extensions
Open Cowork settings and list every Plugin, Skill, and MCP connector you have. Mark which you've actually used this month. Uninstall the dead weight, then install one thing you've been meaning to try. A lean, current toolkit beats a bloated, half-explored one.
The final piece. Automate recurring work with scheduled tasks — daily briefings, weekly reports — and build live artifacts that pull fresh data every time you open them. This is what turns Cowork from a tool into a coworker.
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