UI Widget Developer

What it does

When your agent uses it

• Deployment) — use declarative-agent-developer instead
• Tasks that involve MCP servers
• Tasks that involve Project scaffolding

Example prompts

• “MCP server for Copilot”
• “OpenAI Apps SDK”
• “Copilot widget”
• “/ui-widget-developer”

Requirements

• Node.js

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

1. 1Run /plugin marketplace add modelcontextprotocol/ext-apps
2. 2Run /plugin install mcp-apps@mcp-apps
3. 3Confirm the plugin is available, then invoke the correct ext-apps skill based on user intent

What it can do on your machine

Read from SKILL.md and the folder at commit 1060873. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • npm
  • npx
  • pip
  • python
  • dotnet

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Hosts in commands or code, which the agent is likely to contact:

  • m365.cloud.microsoft

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

UI Widget Developer loads about 6.1k tokens when it runs, and up to ~22k if it reads all its reference files. Until then it costs about 236 tokens; SKILL.md has 2,343 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~236

When it runs · the whole SKILL.md, loaded when a task matches

~6.1k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~22k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• NoteMentions a .env fileSKILL.md:195

  ft/chat/?titleId={M365_TITLE_ID from env/.env.local}

• NoteMentions a .env fileSKILL.md:196

  Other envs: {SHARE_LINK from env/.env.{environment}}

• NoteMentions a .env fileSKILL.md:289

  └── env/.env.local              # MCP_SERVER_URL, MCP_SERVER_DOMAIN

• NoteMentions a .env fileSKILL.md:383

  3. Updates `env/.env.local` with `MCP_SERVER_URL` and `MCP_SERVER_DOMAIN` (first run only)

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 2,343 words (~6,064 tokens).

name

ui-widget-developer

Read the full SKILL.md on GitHub

Files

SKILL.md and 6 other files (references) in plugins/microsoft-365-agents-toolkit/skills/ui-widget-developer of microsoft/work-iq.

• SKILL.md
• references/best-practices.md
• references/copilot-widget-protocol.md
• references/devtunnels.md
• references/mcp-server-pattern.md
• references/plugin-schema.md
• references/widget-patterns.md

Open the folder on GitHubat commit 1060873

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders. This page covers the copy in microsoft/work-iq, which our catalogue first saw on October 7, 2026.

• microsoft/skills.github/plugins/microsoft-365-agents-toolkit/skills/ui-widget-developer