Extending Cowork: plugins, skills, MCP.
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. Skills produce files. MCP connectors reach services. Get the distinction once and the whole marketplace makes sense.
Three extension types, three jobs.
They sound similar, so people conflate them. The clean split:
- Plugins are bundles. A "Sales" plugin might package the Outlook connector + a follow-up-email Skill + prospecting prompt presets. Install one, get the whole workflow.
- Skills are file-format experts. The
docxSkill knows how to build a real Word file;xlsxknows Excel;pptxknows PowerPoint. Skills are how Cowork produces real files instead of chat text. - MCP connectors reach services. Outlook MCP connects to your email, Slack MCP to Slack, Salesforce MCP to your CRM. They're how Cowork touches systems beyond your local files.
.pptx deck. Which extension type actually produces the file?pptx Skill is installed. Let's drill the distinction.
Plugin, Skill, or MCP?
Six things you could add to Cowork. Drop each into the right bucket. The trick: ask "does it bundle, does it build a file, or does it reach a service?"
Check the marketplace before you build.
Most common workflows already have a plugin. Search the marketplace by role before you build anything custom — and vet every install the way you'd vet a browser extension.
Textbook example of the "plugin = bundle" idea: Salesforce and Anthropic announced Claudeforce, and it launches with Salesforce in Claude — a plugin carrying 37 prebuilt sales skills (meeting prep, deal-health review, pipeline review) that reason over live CRM data and route every action back through Salesforce so your business rules still apply. Setup matches the vetting checklist above: an admin connects it once, authentication and permissions are managed centrally, and every seller gets access — no per-user setup, no new permissions model.
Availability, honestly: it is with select pilot customers now, with open beta expected in September 2026 and more skills launching late 2026. You cannot install it today. It is worth knowing because it is the shape enterprise plugins are heading toward — a vendor bundle you connect once, not a skill you build. The same announcement puts Claude across Slack; that side is covered in Claude Tag.
Claude for Small Business (updated 15 September) is the clearest picture yet of what "plugin = bundle" means for a non-developer. One install from the Cowork plugin browser (or say "set me up") now carries 43 workflows and 37 partner connectors — 27 of them new this week, including Shopify, Salesforce, TikTok, Atlassian, Zoom, Xero, Gusto, Square, Stripe and Zapier, on top of the original QuickBooks, PayPal, HubSpot, Canva, Docusign, Google Workspace and Microsoft 365. The workflows are slash-commands: /monday-brief (cash, sales, pipeline, overdue invoices on one page), /speed-to-lead (qualify and answer an inbound inquiry, log it to the CRM), /proposal-builder, /social-content-engine, /close-month. Every one starts in approval mode — Claude drafts and stages, you OK before anything sends, posts or pays — and your existing software permissions hold. It runs on every paid Claude plan; Anthropic recommends Team for more than one person. Installed 900,000+ times since the May launch.
Claude for Financial Advisors (14 September) is the same shape for a regulated profession: a plugin bundling connectors to Addepar, BlackRock, Charles Schwab, Envestnet, iCapital, Orion, SS&C Black Diamond, Wealthbox, Wealth.com, Vanguard and Zocks with eight advisor skills (pre-meeting prep, post-meeting notes and follow-up, portfolio rebalance review, estate and tax brief, alternative investments brief, prospect intake, advisor onboarding, and a compliance skill that screens client-facing language against the SEC Marketing Rule). Availability, honestly: it is live in the Cowork plugin browser, but Anthropic recommends an Enterprise plan for registered advisers because that is where the audit logs live, and firms requesting a new Enterprise licence before the end of September 2026 get a one-time usage credit. Investment recommendations and compliance determinations stay with the human — the plugin stages, the advisor approves.
Vet both the same way as anything else on this page: open the plugin, read which connectors it wants, and connect only the two or three you will actually use in week one.
If your workflow is genuinely unique, the skill-creator Skill lets you bundle your templates, voice, and brand into a custom Skill. But a good one takes one to three hours to build — only worth it for a workflow you'll run at least 5 times. Below that bar, use the base Skills with a detailed prompt.
What would you do?
Four real decisions about extending Cowork. Pick the safe, sensible call.
A lean, current toolkit.
Audit your extensions
Open your Cowork settings and list every Plugin, Skill, and MCP connector installed. Mark which you've actually used this month. Uninstall the dead weight, install one thing you've been meaning to try. A lean, current toolkit beats a bloated, half-explored one.
What you can do now
- Tell a Plugin (bundle) from a Skill (builds files) from an MCP connector (reaches services)
- Search the marketplace by role before building anything custom
- Vet installs like browser extensions — publisher, permissions, ratings
- Use read-only credentials for any production system
- Build a custom Skill only for workflows you'll run 5+ times