Lesson 75 of 2116
Claude Skills — reusable specialized agents
Skills let you package a prompt, tools, files, and configuration into a named capability Claude can invoke on demand.
Lesson map
What this lesson covers
Learning path
The main moves in order
- 1What goes in a Skill
- 2Skills vs. Projects vs. MCP
- 3Claude Skills
- 4SKILL.md
Concept cluster
Terms to connect while reading
Skills are Anthropic's 2025 answer to the question 'how do I teach Claude to do a thing really well, once, and have it work every time?' A Skill is a directory containing a SKILL.md definition file, optional helper scripts, and any reference files Claude needs.
Section 1
What goes in a Skill
- SKILL.md — a markdown spec of the task, including when to invoke and what outputs to produce.
- Helper scripts — Python, JS, shell, whatever. Claude invokes these when it decides the Skill applies.
- Reference files — prompts, examples, schemas, anything the Skill should have in its working set.
- Optionally: subagent definitions, for multi-step Skills.
A minimal SKILL.md
---
name: weekly-report
trigger: When the user asks for a weekly status report
---
# Weekly Report Skill
When invoked:
1. Read the last 7 days of entries from `journal/` using `tools/read-journal.sh`
2. Summarize into 5 bullets: wins, struggles, surprises, next-week, ask.
3. Write output to `out/report-YYYY-MM-DD.md`
4. Return the path and a 1-line summary.Section 2
Skills vs. Projects vs. MCP
Compare the options
| Concept | What it is | Use when |
|---|---|---|
| Claude Project | A persistent chat context with shared files | Repeated conversations on the same topic |
| Skill | Packaged expertise — invoke on demand | Specialized tasks with well-defined I/O |
| MCP Server | A tool-provider Claude can connect to | Integrating external systems (DBs, APIs, file systems) |
Skills run inside the Claude environment. MCP servers run outside and expose tools. Projects are Claude's working memory. You often use all three.
Key terms in this lesson
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