ui-widget-developer

Build MCP servers for Copilot Chat using the OpenAI Apps SDK or MCP Apps SDK widget rendering support (any language). Use this skill when: - Creating MCP servers that integrate with M365 Copilot declarative agents - Building rich interactive widgets (React + Fluent UI) that render in Copilot Chat - Implementing tools that return structuredContent for widget rendering - Adapting an existing MCP server to support Copilot widget rendering - Setting up devtunnels for localhost MCP server exposure - Configuring mcpPlugin.json manifests with RemoteMCPServer runtime Do NOT use this skill for general agent development (scaffolding, manifests, deployment) — use declarative-agent-developer instead. This skill is ONLY for MCP server + widget development. Triggers: "MCP server for Copilot", "OpenAI Apps SDK", "Copilot widget", "structuredContent", "MCP plugin", "devtunnels MCP", "OAI app", "widget rendering", "UI widget"

Agent Skill from microsoft/skills

Copilot Studio

Passes documented load rules

No documented load rule failed.

Warnings (don't change the verdict):

Warning: Description is a single line (CS-DESC-ONELINE)
description spans more than one line
rule · Copilot Studio: Troubleshoot skills that don't load

Microsoft 365 Copilot Preview, Frontier tenants only

Needs changes

Fails: Instructions are under 20,000 characters (M365-INSTRUCTIONS)
instructions are 22,080 characters
rule · Microsoft 365 Copilot: What is a skill

Warnings (don't change the verdict):

Warning: No sign of network access, package installs or authenticated calls (M365-SANDBOX)
SKILL.md mentions pip/uv install, npm/npx install
rule · Microsoft 365 Copilot: Script execution sandbox

An agent can have at most 8 skills. Custom skills aren't available in tenants that use Microsoft Purview Information Barriers.

Compatible isn't the same as safe. These verdicts only say whether a skill's files follow Microsoft's documented load rules. The checker reads files and never runs them, and it doesn't review what a skill or its scripts actually do. Read a skill's instructions and scripts before you add it to an agent.

Standards signals

Meets the agentskills.io required fields.

Frontmatter	Present and parsed Spec: frontmatter
name	Meets the spec (1-64 chars, a-z 0-9 hyphens) Spec: name
description	Present, 1-1,024 characters Spec: description
compatibility	Absent or under 500 characters Spec: compatibility
Name matches folder	Yes (`ui-widget-developer`) Spec: name

Observed from the public SKILL.md at the commit above on 2026-10-23. Not a certification: AAIF and the Agent Skills project don't certify skills. Validate your own skill with skills-ref validate.

Source repo	microsoft/skills
Path	.github/plugins/microsoft-365-agents-toolkit/skills/ui-widget-developer/SKILL.md
Commit checked	`a779d00cf374`
Repo license	MIT
Files	7
Scripts	None
Instructions	22,080 characters
Deepest folder	1 below the skill folder
Rules version	2026-10-22

Re-check the latest version How skill checks work

Is this wrong or out of date? Email us. Skills data built 2026-10-23; rules as of 2026-10-22.

Rule-based checks of public files against Microsoft's documented load rules, not tested in Copilot Studio or Microsoft 365 Copilot. Independent project, not affiliated with Microsoft.