(How to Create a Claude Skill or Plugin for Law and Use It in Claude Cowork)
On February 3, 2026, a single product announcement from Anthropic wiped approximately $285 billion in market capitalization off the stock market in a single trading day. Thomson Reuters dropped 16%. LegalZoom cratered nearly 20%. RELX, the parent company of LexisNexis, fell 14%. Wolters Kluwer lost 13%. The London Stock Exchange Group plunged 8%. The contagion spread to Salesforce, ServiceNow, FactSet, and dozens of other enterprise software companies. Bloomberg called it a “$285 billion rout.” Analysts started calling it the “SaaSpocalypse.”
The catalyst? Anthropic released a set of open-source plugins for its Claude Cowork tool. One of them was a legal plugin that could review contracts, flag risks, triage NDAs, and track compliance. Investors took one look and decided the entire SaaS business model was cooked.
Here’s the part that still gets me: the legal skill at the core of this market panic is, at its heart, a structured markdown file. We’re talking about roughly 250 lines of well-organized pseudo-code, plain text instructions that tell Claude how to think about legal workflows. No compiled binaries. No proprietary algorithms. No infrastructure. Just markdown. And it’s included in the $20/month Claude Pro subscription. That’s less than most attorneys spend on lunch. The full Business Insider breakdown of the stock carnage is here: https://www.businessinsider.com/anthropic-cowork-legal-plugin-publishing-stocks-legalzoom-thomson-reuters-relx-2026-2
So What Are Claude Skills & Plugins, Exactly?
A Claude Skills are a set of instructions, typically written in markdown, that teaches Claude how to approach a specific domain or task in a repeatable, structured way. Think of it as giving Claude a playbook. Instead of prompting from scratch every time you need a contract reviewed or a compliance check run, you write the instructions once, and Claude follows them consistently. Skills include things like domain knowledge (“here’s how our firm handles risk assessment”), step-by-step workflows (“when reviewing an NDA, check these clauses in this order”), and output formatting (“flag issues as green/yellow/red with recommended language”). They’re stored as plain files, organized in folders, and loaded automatically when relevant. Claude Plugins are a bundle that packages one or more skills together with slash commands, MCP connectors, and sub-agents into a single installable unit, while a skill is just a standalone markdown file that teaches Claude how to handle a specific task or domain.
The important thing to understand is that you don’t have to write these from scratch. You can work with Claude itself to build skills and plugins. Describe what you want the workflow to do, what your firm’s processes look like, what outputs you need, and Claude will help you draft, test, and refine the skill. Anthropic has also open-sourced eleven starter plugins on GitHub (https://github.com/anthropics/knowledge-work-plugins/tree/main/legal) that you can customize. The barrier to entry here is remarkably low. If you can write a clear memo, you can write a skill.
Now Let’s Talk About Claude Cowork
Claude Cowork is Anthropic’s desktop tool that takes Claude out of the chat window and puts it to work on your actual files. You point it at a folder on your computer, give it a task, and it plans, executes, and iterates through multi-step workflows on its own. It can read documents, create new files, delete files, organize folders, and coordinate multiple workstreams. If you’ve used Claude Code (the developer-facing terminal tool), Cowork is the same engine with a friendlier interface. It’s essentially Claude Code for laptop professionals who don’t want to learn code. It is currently only available in iOS but Claude recently launched the Claude app for PC, so we’re hopeful to see them in that soon.
What makes Cowork interesting for legal professionals is that it doesn’t just respond to one prompt at a time. You set a goal, and Claude works through it like a (very fast, very thorough) junior associate. It asks for clarification when it needs it, saves outputs directly to your file system, and loops you in on its progress. The plugin system takes this further: install a legal plugin, and Cowork immediately knows your firm’s preferred tone, your risk tolerances, your clause library, and your review workflow, what files to reference as template, etc. It’s a configurable work environment; no more cutting and pasting required.
One more thing worth noting, because I think it says something profound about where we are: Cowork was built entirely by Claude Code in approximately 10 days. An AI coding agent built its own non-technical sibling, and that sibling then crashed the legal tech market. 2026 is going to be wild.
Practical Examples: Skills for Lawyers and Legal Academics
Enough theory; let’s build something. Below are four practical examples, two for practicing attorneys and two for legal academics, showing how you could combine Claude Skills and Cowork to create custom workflows. Each example includes the actual markdown you’d use to create the skill. Markdown is still human-readable, it just gives useful formatting to the text for an LLM. Basically, any complex prompting I do these days is in markdown.
For Lawyers
- Client Intake and Conflict Check Workflow