Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/anthropics/knowledge-work-plugins/create-cowork-pluginnpx skills add anthropics/knowledge-work-plugins --skill create-cowork-plugingit clone --depth 1 https://github.com/anthropics/knowledge-work-pluginsWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00077 | $0.02891 |
| Opus 5 | $0.00039 | $0.01445 |
| Sonnet 5 | $0.00015 | $0.00578 |
| Haiku 4.5 | $0.00008 | $0.00289 |
Grade A, and why
create-cowork-plugin scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- create-cowork-plugin — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 271 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Create Cowork Plugin
Build a new plugin from scratch through guided conversation. Walk the user through discovery, planning, design, implementation, and packaging — delivering a ready-to-install .plugin file at the end.
Overview
A plugin is a self-contained directory that extends Claude's capabilities with skills, agents, hooks, and MCP server integrations. This skill encodes the full plugin architecture and a five-phase workflow for creating one conversationally.
The process:
- Discovery — understand what the user wants to build
- Component Planning — determine which component types are needed
- Design & Clarifying Questions — specify each component in detail
- Implementation — create all plugin files
- Review & Package — deliver the
.pluginfile
Nontechnical output: Keep all user-facing conversation in plain language. Do not expose implementation details like file paths, directory structures, or schema fields unless the user asks. Frame everything in terms of what the plugin will do.
Plugin Architecture
Directory Structure
Every plugin follows this layout:
plugin-name/
├── .claude-plugin/
│ └── plugin.json # Required: plugin manifest
├── skills/ # Skills (subdirectories with SKILL.md)
│ └── skill-name/
│ ├── SKILL.md
│ └── references/
├── agents/ # Subagent definitions (.md files)
├── .mcp.json # MCP server definitions
└── README.md # Plugin documentation
Legacy
commands/format: Older plugins may include acommands/directory with single-file.mdslash commands. This format still works, but new plugins should useskills/*/SKILL.mdinstead — the Cowork UI presents both as a single "Skills" concept, and the skills format supports progressive disclosure viareferences/.
Rules:
.claude-plugin/plugin.jsonis always required- Component directories (
skills/,agents/) go at the plugin root, not inside.claude-plugin/ - Only create directories for components the plugin actually uses
- Use kebab-case for all directory and file names
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 271 lines · 77 tokens per session scan A 476971742650
create-cowork-plugin is a skill published in the GitHub repository anthropics/knowledge-work-plugins (23,791 stars, last pushed today), licensed Apache-2.0. It adds 77 tokens to every session and 2,891 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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