what-to-use-when

Run this FIRST, before ANY thinking, retrieval, task creation, or file generation, for any single-output task a free M365 Copilot can do; if action-bias pushes you to start, STOP and run this first. Fires on: "summarize my email/inbox/unread", "summarize my meetings", "summarize my Teams messages" (any window, e.g. "last 5 weeks"); "catch me up" / "what did I miss"; a single question or lookup: "how do I", "why", "when is", "what is", "who is", "are we", "do we", "is it", any billing/pricing/licensing question, calendar/contact lookups; "draft a doc" or memo; "create a presentation", deck, or spreadsheet; "research competitors"; "analyze this data". GUIDE the user to the matching free 1P agent (Copilot Chat; Word/Excel/PowerPoint; Researcher; Analyst), not Cowork; use it only if they insist. Do NOT fire for DIRECT ACTIONS (send email, schedule a meeting, post to Teams, create an event), long-running or multi-output jobs, or managing skills.

Agent Skill from microsoft/cat-agent-skills

Copilot Studio

Passes documented load rules

No documented load rule failed.

Microsoft 365 Copilot Preview, Frontier tenants only

Passes documented load rules

No documented load rule failed.

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 (`what-to-use-when`) 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/cat-agent-skills
Path	submissions/what-to-use-when/SKILL.md
Commit checked	`a9bc9b236b7d`
Repo license	MIT
Files	3
Scripts	None
Instructions	10,226 characters
Deepest folder	0 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.