OpenWebUI Extensibility Builder

An agent skill for designing, building, and reviewing OpenWebUI extensibility artifacts.

This skill helps the agent choose the right OpenWebUI surface before implementation, then build against the real runtime contract instead of guessing. It covers:

• native OpenWebUI Tools
• Action, Filter, and Pipe Functions
• in-product OpenWebUI markdown skills
• Rich UI embeds and iframe runtime behavior
• OpenAPI tool servers
• MCP integrations
• Pipelines
• porting browser prototypes into OpenWebUI

Install

The official skills CLI command is add.

npx skills add MRNAQA/openwebui-extensibility-builder

Useful variants:

# Preview the skill without installing it
npx skills add MRNAQA/openwebui-extensibility-builder --list

# Install globally
npx skills add MRNAQA/openwebui-extensibility-builder -g

# Install only to a specific agent
npx skills add MRNAQA/openwebui-extensibility-builder -a opencode
npx skills add MRNAQA/openwebui-extensibility-builder -a claude-code

You can also install from the full GitHub URL:

npx skills add https://github.com/MRNAQA/openwebui-extensibility-builder

What The Skill Does

This skill is optimized for requests such as:

• "Build an OpenWebUI tool for ..."
• "Should this be a Tool, Action, Filter, Pipe, OpenAPI server, MCP integration, or Pipeline?"
• "Port this browser prototype into OpenWebUI"
• "Build a Rich UI preview in OpenWebUI"
• "Why is my OpenWebUI iframe blank / too tall / styled wrong?"
• "Create an OpenWebUI skill or helper package"

The skill includes:

• a main SKILL.md with architecture and implementation rules
• references/openwebui-notes.md with a docs map, architecture matrix, and runtime rules
• references/iframe-rich-ui-debugging.md with a generic Rich UI / iframe debugging runbook

Repository Shape

This repository is intentionally minimal because the skills ecosystem can install a public GitHub repo directly as long as it contains a valid SKILL.md.

openwebui-extensibility-builder/
├── SKILL.md
├── README.md
└── references/
    ├── openwebui-notes.md
    └── iframe-rich-ui-debugging.md

Publishing And Discovery Notes

There are two separate concerns:

1. Installability

If the repo is public and has a valid root SKILL.md, users can install it immediately with:

npx skills add MRNAQA/openwebui-extensibility-builder

2. skills.sh discovery and ranking

The public skills.sh directory and npx skills find are backed by anonymous install telemetry from the skills CLI. In practice, this means the repo becomes discoverable as people install it. There is no extra publishing manifest required for basic listing.

Important Limitation: "Official" Listing

The skills.sh Official page is curated around skills published by the makers of the underlying technology. For this skill to appear as an official OpenWebUI skill, it would likely need one of these:

• the repo to live under an OpenWebUI-owned GitHub organization
• explicit adoption or endorsement by OpenWebUI maintainers
• inclusion by the skills.sh maintainers in their official-maker categorization

Publishing this repo under MRNAQA can still make it installable and discoverable on skills.sh, but it does not automatically make it an "Official" maker-published skill.

Development

To edit locally, update the skill files in this repo and keep the relative references intact.

Basic validation:

npx skills add /path/to/openwebui-extensibility-builder --list

After pushing to GitHub:

npx skills add MRNAQA/openwebui-extensibility-builder --list

Source Material

This public repo was packaged from a working local helper skill that was already being used for OpenWebUI architecture guidance and Rich UI debugging.