Claude Cowork Plugins: What They Are and How They Compare to Skills
Plugins, connectors, and skills all extend Cowork, and the names get mixed up constantly. Here's what each layer actually does.
Quick Answer: Cowork has three extension layers that people lump together as "plugins." Plugins from Cowork's marketplace add packaged capabilities to the app. Connectors (built on MCP) link Cowork to external services like your email, calendar, and business tools. Skills (SKILL.md files) teach Cowork how to perform specific jobs at an expert level. Capabilities, access, and expertise. Most real setups use all three: a connector to reach your data, and a skill to do something excellent with it.
The three layers, untangled
Plugins: what Cowork can do. Cowork ships with a plugin marketplace inside the app. Plugins package up capabilities and vertical toolsets; Anthropic has leaned into this with bundles for legal work, small business, and marketing operations. Think of plugins as feature packs for the Cowork environment itself.
Connectors: what Cowork can reach. Connectors give Cowork access to external services and data sources, built on MCP (Model Context Protocol), the open standard for wiring AI agents to tools. A calendar connector lets Cowork see your schedule. A browser tool lets it research the live web. Connectors answer "can Cowork touch this system at all." For the protocol details, see what is MCP.
Skills: how well Cowork does the job. A skill is a SKILL.md file containing an expert's method for one task: how a strong proposal is structured, what a rigorous landing page audit checks, how a professional research summary is organized. Cowork reads skills natively and applies them automatically when a task matches. Skills answer "will the output be expert-grade or generic." Full primer: what is SKILL.md.
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Why the distinction matters in practice
Mixing these up leads to the two most common Cowork frustrations.
"I installed things but the output is still mediocre." You added plugins and connectors: more capability, more access, same generalist judgment. Quality comes from skills.
"My skill can't do X." The skill knows the method but lacks access. A reporting skill can't summarize your analytics if no connector reaches your analytics.
The mental model: connectors and plugins are hands, skills are craft. Hands without craft produce clumsy work. Craft without hands can't reach the materials.
A concrete stack for a small business
Take a recurring competitor report. A browser tool gives Cowork live web access (reach). A research skill like deep-research-team structures the investigation and the output (craft). A scheduled Cowork task runs it monthly into your reports folder (automation). Each layer does its one job, and the result is a deliverable you'd otherwise pay hours for.
Where to get each layer
Plugins: Cowork's built-in marketplace, inside the app. Connectors: Claude's connector settings plus the growing MCP ecosystem; Agensi also runs an MCP directory for discovering servers. Skills: Agensi is the marketplace, with 2,000+ skills from KYC-verified creators, each security-scanned before listing, most $5 to $29, installed in about 30 seconds.
If you extend Cowork with anything third-party, provenance is the security question that matters. Skills and MCP servers are instructions and access you're handing your agent, which is why every Agensi listing shows its scan status and declared permissions. Deeper dive: are AI agent skills safe.