plugin-builder SKILL.md skillA
plugin-builder from vellum-ai/vellum-assistant is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add vellum-ai/vellum-assistant/plugin-builder@git:20260917.b9a2adfPins git:20260917.b9a2adf in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- vellum-ai/vellum-assistant
- Path
skills/plugin-builder/SKILL.md- Versions recorded
- 8
- Latest version
- git:20260917.b9a2adf, committed Sep 17, 2026
- First version recorded
- Jul 15, 2026
- Size
- 12,411 bytes
- Repository stars
- 1,483
- License
- MIT
Use when the user wants to build, scaffold, ship, or edit a Vellum plugin that bundles multiple surfaces (hooks, tools, skills, and more) into one installable package.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Plugin Builder Build on top of Vellum with plugins. A plugin bundles multiple surfaces into a single installable package that extends what an assistant can do. Plugins are in beta. The peer-dep range you declare is what gets you load. Treat everything you write as something that can break between Vellum releases until 1.0 ships, and pin a real range. ## What is a plugin? A plugin is a directory in the assistant's workspace (`<workspaceDir>/plugins/<name>/`) that groups different surfaces into one cohesive capability. The assistant can build plugins directly in this folder or install one from the community via the CLI: ``` assistant plugins install <name> ``` Plugins can also be discovered and managed from the Plugins tab in the app, or searched from the CLI with `assistant plugins search`. The catalog is a curated allowlist that the Vellum team approves and curates. ## The surfaces a plugin can bundle A single plugin can contribute several different kinds of behavior. Each surface is discovered by convention from a named subdirectory. Missing directories are simply skipped, so a plugin contributes only what it ships. …
Read the whole file at its exact version.
How to install
mdr add vellum-ai/vellum-assistant/plugin-builder@sha256:0470e5eeb1c7c390The line at the top of this page pins the label git:20260917.b9a2adf, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_rli5dj2sh3gk4kz4)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 8 versions of this file, between Jul 15, 2026 and Sep 17, 2026, about one every 9 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260917.b9a2adf latest | 2026-09-17 | b9a2adf | 12,411 B | A | view · diff |
| git:20260914.25fbd03 | 2026-09-14 | 25fbd03 | 11,971 B | A | view · diff |
| git:20260911.aece348 | 2026-09-11 | aece348 | 11,960 B | A | view · diff |
| git:20260903.5802532 | 2026-09-03 | 5802532 | 11,960 B | A | view · diff |
| git:20260821.21c4ce1 | 2026-08-21 | 21c4ce1 | 12,193 B | A | view · diff |
| git:20260820.1ae37bb | 2026-08-20 | 1ae37bb | 11,298 B | A | view · diff |
| git:20260716.2ed537f | 2026-07-16 | 2ed537f | 11,290 B | A | view · diff |
| git:20260715.5b9fbf1 | 2026-07-15 | 5b9fbf1 | 11,147 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (12411 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
vellum-ai/vellum-assistant · 1,483 stars · license MIT · pushed 2026-11-08 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_rli5dj2sh3gk4kz4 GET https://markdownregistry.com/api/v1/resolve?ref=vellum-ai/vellum-assistant/plugin-builder GET https://markdownregistry.com/api/v1/blob/0470e5eeb1c7c39067050649d88e1c060fc02a7a10465e09f78a13054542dad0
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
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