screenshot

Screenshotting

Take screenshots to see what's on screen. Captures persist as files (unlike browsermcp snapshots which only exist in context).

Quick Reference

# Capture specific app window
${CLAUDE_SKILL_DIR}/scripts/look.py --app Ghostty

# Capture window by title match
${CLAUDE_SKILL_DIR}/scripts/look.py --app Chrome --title "LinkedIn"

# Capture full screen
${CLAUDE_SKILL_DIR}/scripts/look.py --screen

# List available windows
${CLAUDE_SKILL_DIR}/scripts/look.py --list

List windows grouped by category

${CLAUDE_SKILL_DIR}/scripts/look.py --categories

List only browser windows

${CLAUDE_SKILL_DIR}/scripts/look.py --category browsers

Native resolution (skip resize)

${CLAUDE_SKILL_DIR}/scripts/look.py --app Safari --native

**Categories:** browsers, terminals, editors, communication, documents, media, other

## When to Use

**Reactive (user asks):**
- "Have a look at this"
- "Can you see what's on screen?"
- "What does it look like?"
- "Check the browser"

**Proactive (verify state):**
- After uncertain CLI operations (did it background?)
- When tool prompt state is unclear
- After browsermcp actions when snapshot isn't enough
- To verify visual changes actually happened

**Documentation:**
- Capture steps in a workflow
- Before/after comparisons
- Bug evidence with screenshots

## When NOT to Use

- Browser-only tasks where browsermcp snapshot suffices
- When you just need to describe what's visible
- High-frequency captures that would clutter the directory

## Anti-Patterns

| Pattern | Problem | Fix |
|---------|---------|-----|
| Capture without purpose | Clutters context | Only screenshot when you need the visual |
| Skip --list first | Wrong window captured | List windows to find exact app/title |
| Native on large screens | Huge files, slow upload | Use default 1568px resize |

## Resolution Strategy

Default: 1568px max dimension (~1,600 tokens, optimal for API)

| Option | Tokens | Use case |
|--------|--------|----------|
| Default (1568px) | ~1,600 | Full detail, no resize penalty |
| `--max-size 735` | ~500 | Quick look, text readable |
| `--native` | varies | When original resolution needed |

**Why 1568px:** Images larger than this get resized server-side anyway. Pre-resizing avoids upload latency while getting the same visual fidelity.

## Output

**Ephemeral (no path):** Screenshots go to `/tmp/claude-screenshots/` — auto-cleaned by OS, won't clutter project directories:

/tmp/claude-screenshots/2025-12-15-143022-chrome.png

**Persistent (explicit path):** For documentation workflows, specify where screenshots should live:
```bash
look.py --app Chrome ./docs/step3.png

Design rationale: Quick looks are ephemeral by default. Documentation requires intentional placement. If a subagent is documenting, it should think about where artifacts belong.

How It Works

1. Window enumeration: Uses macOS CGWindowList API (pure Quartz, no AppleScript)
2. Capture: Uses screencapture -l<windowid> for windows, screencapture -x for screen
3. Resize: Uses sips --resampleHeightWidthMax for efficient scaling

Key capability: Can capture windows even when covered or minimized.

Limitations

Scrollback: Only captures visible viewport. If content scrolled off screen, it won't be in the screenshot. Workaround: increase window size or pipe output to file.

Multiple monitors: Untested. --screen with -m flag captures main monitor only.

Window selection: Takes first match when multiple windows match filters. No "frontmost" heuristic yet.

Integration with browsermcp

browsermcp's browser_screenshot injects images directly into context but doesn't persist them as files. Use this skill when you need:

• Screenshots that persist beyond the conversation
• Captures of non-browser apps
• Captures of windows behind the browser
• Files to upload to Drive or include in docs

Permissions

Requires Screen Recording permission in System Preferences > Privacy & Security.

If capture fails with "check Screen Recording permissions", the user needs to grant permission to the terminal app (Ghostty, Terminal, iTerm, etc.).