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Skills and plugins, specialisation on demand
A skill is a specialisation loaded to handle a specific domain, a plugin bundles several of them into a single installable package.
A skill is a specialisation Claude loads for a specific domain or for a repeated way of doing something, a way of doing something written once and replayed identically afterwards. A plugin goes further: it bundles several skills, and sometimes other elements such as a link to an external service, into a single installable package. Installing a plugin therefore activates all of its parts at once, without needing to add them one by one.
What each one concretely brings
An isolated skill stays targeted: it knows how to do one precise thing, summarise a report in the format a department requires, for example, and nothing more. It suits situations where a single need comes up regularly in your work. A plugin becomes useful when several needs from the same team come up together: a support team handling complaints, for instance, benefits from having a single package rather than several separate elements to find and activate one at a time.
Plugin "Support client"
- Compétence : réponse type aux réclamations
- Compétence : résumé de ticket en trois lignes
- Lien : messagerie du serviceRead the description that comes with a skill or a plugin before activating it: it is the only place where its author states what it does and when it applies. A vague description leaves you with no way to judge, and this shortcoming matters whether or not Claude uses it to choose, a mechanism no public source describes.
Before installing anything
A skill or a plugin adds a capability Claude did not have before, which deserves the same caution as a connected folder: know precisely what it touches before activating it. First identify what your team actually needs, compare that with what already exists in Cowork's extension settings, and ask your administrator if any doubt remains about what a particular piece really does. The lesson on Cowork as the default mode lays out the basics of what Claude can already do with no extension added, which helps judge whether a skill or a plugin genuinely brings something new.
An isolated skill versus a plugin
| Extension | What it brings | Number of pieces | Typical example | When to consider it |
|---|---|---|---|---|
| A skill | A specialisation targeted at a specific domain or a repeated way of doing something | A single building block, callable on its own | Summarising reports according to a format the department requires | A single recurring need, isolated from the rest |
| A plugin | A grouping of several skills and sometimes a link to an external service | Several building blocks combined into a single package | A complete pack for an entire team, customer support or accounting | Several needs from the same team that come up together |
A team opens their organisation's internal catalogue and requests the installation of an entry named Customer support. The installation screen presents four checkable lines, each with a different label. The team ticks only the line labelled Ticket summary, then confirms. Its list of active specialisations then shows one entry.
Write in one sentence what this situation establishes, and in one sentence what it does not establish.
What this establishes: It establishes that the catalogue entry grouped several elements offered separately at installation, and that it is possible to keep only one of them.
What this does not establish: It does not establish what the three lines left aside contained, nor whether the team can add them later without going through the same approval again.
The three most common miscalibrations
- Too broad This situation shows that any entry in an internal catalogue installs freely, with no approval ever requested.
- Too narrow This situation shows only that a team ticked a box on an installation screen, which teaches nothing in particular.
- Beside the point It establishes that the ticked line was the most useful of the four for this team's work.
- A skill is a specialisation loaded to handle a specific domain or a repeated way of doing something, callable on its own.
- A plugin bundles several skills, and sometimes other elements such as a link to an external service, into a single installable package.
- Installing a plugin activates all of its parts together, without needing to add them one by one yourself.
- The description that comes with a skill or a plugin determines whether it is offered at the right moment for the right task.
Open Cowork's extension settings and read the description of two of them, without installing anything. Note, for each one, what it says it touches and what it does not say.
These points depend on an interface or a rule that may have changed since this was written. Check them on your own screen before relying on them.
- The exact label of the menu or library that presents the skills and plugins available in Cowork, along with the precise detail of the installation or activation procedure, is not confirmed by the September 2026 record for this text: it should be checked directly in the interface before any explanation given to a colleague.
- The way Claude chooses to load a skill is not described by any public source recorded on 2 September 2026. This lesson therefore bases no advice on it.
Every datable claim in this lesson links here to the public text behind it. A source that does not open proves nothing.
- Anthropic, using skills in Claude consultée le 2026-09-02
- Anthropic, using plugins in Claude, and what a plugin bundles consultée le 2026-09-02
- Anthropic, browsing skills, connectors and plugins in one directory consultée le 2026-09-02