Build an AI Article Summarizer with Skills in 10 Minutes – Boost Writing Speed Tenfold

This article is the third installment of the “Agent Skills Best Practices” series and provides a hands‑on guide to building a practical Skill that enables Claude to automatically summarize any article.

Why custom Skills?

When you repeatedly ask Claude to summarize long technical documents you must re‑specify the format, level of detail, and output location each time. A Skill lets you teach Claude a complete workflow once and invoke it with a single command.

What is a Skill?

A Skill is simply a folder containing a SKILL.md file. The file defines the Skill’s name, description, argument hints, allowed tools, and the model to use. Claude scans all Skills at startup, reads the metadata (≈100 tokens), and loads the full instruction (‑5000 tokens) only when the Skill is needed, preserving context size.

Practical Project: Article Summarizer Skill

The guide walks through creating an "article‑summarizer" Skill that asks the user which article to process, how detailed the summary should be, reads the file, generates a structured Markdown summary, and writes the result back.

Step 1 – Create the file structure

mkdir -p .claude/skills/article-summarizer
cd .claude/skills/article-summarizer

touch SKILL.md
mkdir -p scripts references

The directory layout is:

article-summarizer/
├── SKILL.md          # core instruction + metadata
├── scripts/          # optional helper scripts
└── references/       # optional example files

Step 2 – Write SKILL.md

The file starts with a YAML front‑matter that defines the Skill’s metadata:

---
name: article-summarizer
description: Summarize an article and generate a structured summary. Use when you need a quick overview of long technical documents.
argument-hint: [article-path]
allowed-tools: Read Write AskUserQuestion
model: inherit
---

Key fields:

name : unique identifier used as /article-summarizer to invoke the Skill.

description : tells Claude when the Skill is appropriate; a clear use‑case is essential.

argument-hint : hints that the user should provide an article path.

allowed-tools : limits the Skill to safe operations (read, write, ask).

model : inherits the current session’s model.

After the front‑matter, the Markdown body describes the workflow:

# Article Summarizer
## Your task
When the user wants an article summary, follow these steps.

## Step 1: Collect information
- Ask the user to choose an article (use <code>Glob</code> to list Markdown files).
- Ask the user for the desired detail level (short / medium / detailed).

## Step 2: Read the article
1. Verify the file exists.
2. Read the full content.
3. Identify headings and sections.

If the article exceeds 10 000 words, warn the user about possible latency.

## Step 3: Generate the summary
### Short summary
- Core theme (one sentence)
- 3‑5 key points (one sentence each)
- Main conclusion (one sentence)

### Medium summary
- Overview paragraph
- 3‑5 main arguments with brief supporting details
- Key data and citations
- Conclusion paragraph

### Detailed summary
- Full outline
- Detailed per‑section summaries
- Important quotes with sources
- Author’s viewpoint analysis
- Final implications

## Step 4: Format output
Use the following Markdown template:

```markdown
# Article Summary: {title}
**Source**: {path}
**Generated at**: {timestamp}
**Summary type**: {short/medium/detailed}

## Core Theme
{one‑sentence theme}

## Key Points
1. {point 1}
2. {point 2}
3. {point 3}
…

## Detailed Content
{expanded sections}

## Conclusion
{final statement}
```

## Step 5: Save the summary
Write the file next to the original with the name <code>{original‑name}-summary.md</code> (UTF‑8). Notify the user of the path.

Step 3 – Test the Skill

Three testing approaches are shown:

Direct command: /article-summarizer docs/my-article.md Natural‑language trigger: type “Help me summarize this article”.

Interactive use: /article-summarizer and answer Claude’s questions.

Step 4 – Debug & Optimize

Common pitfalls and fixes:

Skill not selected : ensure the description clearly states the use‑case.

AskUserQuestion not firing : explicitly mention “use AskUserQuestion tool”.

Wrong output format : provide a concrete Markdown template instead of vague instructions.

Large files : add a warning for articles >10 000 words or offload work to a sub‑Agent.

Advanced Techniques

Dynamic context injection

Use the !\`find . -name "*.md" -type f | head -20\` syntax to automatically list Markdown files when the Skill loads.

Running in a sub‑Agent

For heavy analysis, set context: fork so the Skill runs in an isolated sub‑Agent, keeping the main conversation lightweight.

Hooks for post‑processing

Define a PostToolUse hook that runs a formatting script after the Write tool finishes:

---
name: article-summarizer-pro
description: Professional article summarizer with auto‑formatting
hooks:
  PostToolUse:
    - matcher: "Write"
      type: command
      command: "./scripts/format-markdown.sh"
---

Best Practices

Clear description : write “When the user needs a quick understanding of a long article, use this Skill.”

Specific instructions : detail the exact summary structure instead of vague “generate a good summary”.

Robust error handling : cover missing files, oversized files, and unsupported formats.

Limit allowed tools : only enable the tools the Skill truly needs.

Provide examples : place sample files in references/ for Claude to learn expectations.

Keep it concise : aim for ≤500 lines; split into multiple Skills if it grows larger.

Version control : store Skills in a Git repository to track changes, share with teammates, and roll back.

Test edge cases : empty files, huge files, malformed markup, nonexistent paths.

Extension Ideas

Support additional formats (PDF, Word, web pages) via conversion scripts in scripts/.

Batch processing of an entire directory.

Customizable templates stored in assets/.

Integrate external services (Notion, Obsidian, translation APIs).

Add intelligent analysis features: keyword extraction, topic classification, sentiment analysis, similar‑article recommendation.

Conclusion

Creating a Claude Code Skill is straightforward: create SKILL.md, write clear metadata, describe the workflow in Markdown, then test and iterate. By following the steps, examples, and best‑practice checklist in this guide you can build reliable, reusable Skills for article summarization and many other repetitive tasks.