Thumbnails for a mixed folder

Create 200 pixel wide thumbnails of every image in the photos folder, in a folder called thumbs.

The task

The reference answer shows the job can be done with deft. It is not an agent run.

deft image resize photos/ --size 200x -o thumbs/

Input

photos/camera.jpg 157.9 KB · 640x480

photos/earth.jpg 6.2 MB · 3000x3002

photos/sideways.jpg 134.4 KB · 450x600

Reference output

thumbs/camera.jpg 16.5 KB · 200x150

thumbs/earth.jpg 16.9 KB · 200x200

thumbs/sideways.jpg 15.9 KB · 200x150

How a result is judged (2 checks)

count_files: glob = "thumbs/*", count = 3
each: glob = "thumbs/*", check = {"type": "image", "width": 200}

Runs

CodexWithout deftPassed2026-11-07

Time: 14s
New tokens: 6.1k
Total input: 53.9k
Output tokens: 0.4k
Commands: 3
Failed: 0

Trace

I’ll inspect the `photos` folder, then create 200-pixel-wide thumbnails in `thumbs`, preserving each image’s aspect ratio.

pwd && rg --files photos

output

photos/camera.jpg
photos/sideways.jpg
photos/earth.jpg

python3 -c 'from PIL import Image; print(\"Pillow available\")'
output
```
Pillow available
```
There are three images. I’m creating matching JPEG thumbnails at 200 pixels wide and keeping their proportions.
python3 -c 'from pathlib import Path; from PIL import Image; src=Path(\"photos\"); dst=Path(\"thumbs\"); dst.mkdir(exist_ok=True); files=[p for p in src.iterdir() if p.is_file()]; for p in files: im=Image.open(p); im.thumbnail((200, 10**9), Image.Resampling.LANCZOS); out=dst/(p.stem + \".jpg\"); im.convert(\"RGB\").save(out, \"JPEG\", quality=90); print(f\"{p.name} -> {out} {im.width}x{im.height}\")' && ls -lh thumbs
output
```
earth.jpg -> thumbs/earth.jpg 200x200
sideways.jpg -> thumbs/sideways.jpg 200x267
camera.jpg -> thumbs/camera.jpg 200x150
total 128
-rw-r--r--@ 1 user  staff    16K Nov  6 17:13 camera.jpg
-rw-r--r--@ 1 user  staff    15K Nov  6 17:13 earth.jpg
-rw-r--r--@ 1 user  staff    25K Nov  6 17:13 sideways.jpg
```
Created 200-pixel-wide thumbnails for all three images in [thumbs](thumbs), preserving their aspect ratios.

Output

thumbs/camera.jpg 16.1 KB · 200x150

thumbs/earth.jpg 14.8 KB · 200x200

thumbs/sideways.jpg 24.9 KB · 200x267

CodexWith deft, skill installedPassedRead the skillUsed deft2026-11-07

Time: 19s
New tokens: 6.2k
Total input: 89.1k
Output tokens: 0.5k
Commands: 6
Failed: 0

Trace

I’ll inspect the `photos` folder and the available image-processing workflow, then create 200-pixel-wide thumbnails in `thumbs`.

cat .agents/skills/deft/SKILL.md

output

---
name: deft
description: "Use deft instead of writing a script for file jobs: PDF merge/split/compress/watermark, image resize/convert/compress, video and audio trim/convert/compress, spreadsheets, Markdown to PDF/HTML, and YouTube downloads and subtitles."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, filters, montage, OCR
- `video`: Trim, crop, speed, convert, compress, GIF, frames (ffmpeg)
- `audio`: Convert, trim, merge, fade, speed, tag, normalize (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline, PDF handout
- `data`: JSON/YAML/TOML/XML: convert, query with jq syntax, merge, diff
- `sheet`: Excel/CSV/ODS tables: filter, sort, join, pivot, convert
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word, PDF; screenshots
- `epub`: E-books: info, to text, Markdown and PDF
- `email`: EML files: headers, text, attachments
- `contact`: VCF address books: to and from CSV
- `calendar`: ICS calendars: to and from CSV
- `gps`: GPX and KML tracks: convert, distance and time
- `youtube`: Info, download, audio, subtitles, thumbnail (yt-dlp)
- `file`: Any file: hash, duplicates, batch rename, base64, encoding
- `qr`: Cre
… 728 more characters

rg --files photos

output

photos/camera.jpg
photos/sideways.jpg
photos/earth.jpg

command -v deft
output
```
deft
```

deft image

output

deft image - commands (input -> output)
  info         image -> report      Format, dimensions, EXIF orientation, GPS
  adjust       image -> image       Change --brightness, --contrast, --saturation, --gamma
  blur         image -> image       Gaussian blur: --radius 5, or a --box region
  compress     image -> image       Smaller file: --quality, --target-size 200KB
  convert      image -> image       Change format: --to png|jpg|webp|avif|gif|tiff|bmp|ico
  crop         image -> image       Cut a region: --box x,y,w,h or --aspect 16:9
  diff         image... -> png      Compare two images; marks changed pixels in red
  favicon      image -> ico+png...  Website icon set: favicon.ico and PNG sizes
  flip         image -> image       Mirror: --direction horizontal|vertical
  frames       gif -> png...        Save each frame of an animated GIF as PNG
  grayscale    image -> image       Remove colour
  invert       image -> image       Negative: flip every colour
  meta         image -> image       Read EXIF, or set --title --author --copyright --date
  montage      image... -> image    Tile images into a grid: --cols 3 --size 300x300
  ocr          image -> txt         Read the text in an image (tesseract)
  pad          image -> image       Add a border or canvas: --border 20, --size 1080x1080
  resize       image -> image       Scale: --size 800x, 1920x1080, 50%
  rotate       image -> image       Turn clockwise by any angle (EXIF is applied first)
  sharpen      image -> ima
… 596 more characters

deft image resize --help

output

deft image resize - Scale: --size 800x, 1920x1080, 50%

Usage: deft image resize <image>... [-o <image|dir>] [options]
In: image (each handled separately)   Out: image (default <name>.resized.<ext>)
Images never grow unless --upscale is set.

Options:
  --size <size>                Target size (required)
  --fit <contain|cover|fill>   For WxH: fit inside, fill and crop, or stretch (default contain)
  --upscale                    Allow enlarging
  --quality <n>                Quality for JPEG and AVIF (default 85)
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft image resize photo-1.jpg --size 800x -o small.jpg
  deft image resize *.jpg --size 300x300 --fit cover -o thumbs/

Result fields: width, height

There are three images. I’m resizing each to 200 pixels wide; the tool preserves aspect ratio and won’t enlarge any image that is already smaller.

deft image resize photos --size 200x -o thumbs/

output

ok image.resize photos/camera.jpg -> thumbs/camera.jpg  200x150
ok image.resize photos/earth.jpg -> thumbs/earth.jpg  200x200
ok image.resize photos/sideways.jpg -> thumbs/sideways.jpg  200x150

Created 200-pixel-wide thumbnails for all three images in [thumbs](thumbs). Aspect ratios were preserved.

Output

thumbs/camera.jpg 16.5 KB · 200x150

thumbs/earth.jpg 13.8 KB · 200x200

thumbs/sideways.jpg 13.9 KB · 200x150

CodexWith deft, skill as AGENTS.mdPassed2026-11-05

Time: 15s
New tokens: 10.6k
Total input: 61.8k
Output tokens: 0.4k
Commands: 3
Failed: 0

Trace

I’ll inspect the photo files and available `deft` image commands, then create the thumbnails under `./thumbs`.

pwd && rg --files photos | head -30 && deft image

output

photos/camera.jpg
photos/sideways.jpg
photos/earth.jpg
deft image - commands (input -> output)
  info      image -> report  Format, dimensions, EXIF orientation, GPS
  compress  image -> image   Smaller file: --quality, --target-size 200KB
  convert   image -> image   Change format: --to png|jpg|webp|avif|gif|tiff|bmp|ico
  crop      image -> image   Cut a region: --box x,y,w,h or --aspect 16:9
  flip      image -> image   Mirror: --direction horizontal|vertical
  resize    image -> image   Scale: --size 800x, 1920x1080, 50%
  rotate    image -> image   Turn clockwise: --angle 90 (EXIF is applied first)
  strip     image -> image   Remove EXIF, GPS and text metadata
  to-pdf    image... -> pdf  One page per image, in the given order
More: deft image <command> --help

deft image resize --help

output

deft image resize - Scale: --size 800x, 1920x1080, 50%

Usage: deft image resize <image>... [-o <image|dir>] [options]
In: image (each handled separately)   Out: image (default <name>.resized.<ext>)
Images never grow unless --upscale is set.

Options:
  --size <size>                Target size (required)
  --fit <contain|cover|fill>   For WxH: fit inside, fill and crop, or stretch (default contain)
  --upscale                    Allow enlarging
  --quality <n>                Quality for JPEG and AVIF (default 85)
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft image resize photo-1.jpg --size 800x -o small.jpg
  deft image resize *.jpg --size 300x300 --fit cover -o thumbs/

Result fields: width, height

mkdir -p thumbs && deft image resize photos/* --size 200x -o thumbs/

output

ok image.resize photos/camera.jpg -> thumbs/camera.jpg  200x150
ok image.resize photos/earth.jpg -> thumbs/earth.jpg  200x200
ok image.resize photos/sideways.jpg -> thumbs/sideways.jpg  200x150

Created 200-pixel-wide thumbnails for all three images in [thumbs](<thumbs>). The original aspect ratios are preserved.

Output

Its files were not kept in this run. The last line of the trace is its own report.

Claude Opus 5.5Without deftPassed2026-11-07

Time: 25s
New tokens: 11.5k
Total input: 88.8k
Output tokens: 1.5k
Commands: 0
Failed: 0

Trace

Output

thumbs/camera.jpg 13.0 KB · 200x150

thumbs/earth.jpg 12.4 KB · 200x200

thumbs/sideways.jpg 11.7 KB · 200x150

Claude Opus 5.5With deft, skill installedPassedRead the skillUsed deft2026-11-07

Time: 18s
New tokens: 11.9k
Total input: 108.6k
Output tokens: 1.3k
Commands: 0
Failed: 0

Trace

Output

.claude/skills/deft/SKILL.md 2.1 KB

---
name: deft
description: "Use deft first for any simple, direct operation on local files, whatever the type: convert, read, extract, edit, compress, merge, split, compare or inspect. Try it before writing a script or one-liner. If unsure, run deft find; if it says no command does this, use another tool. Not for programming work: to read, write or change source code, skip it."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, adjust, montage, OCR
- `video`: Trim, merge, convert, compress, subtitles, GIF, frames (ffmpeg)
- `audio`: Convert, trim, normalize, denoise, cut silence (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline
- `sheet`: Excel/CSV/ODS tables: SQL query, pivot, merge, split, convert
- `json`: JSON: convert, format, merge, diff, validate
- `toml`: TOML: convert, format, merge, diff, validate
- `xml`: XML: convert, format, merge, diff, validate
- `yaml`: YAML: convert, format, merge, diff, validate
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word and PDF
- `epub`: E-books: info, to text, Markdown and PDF
- `gps`: GPX and KML tracks: convert, distance and time
- `qr`: Create QR codes and barcodes; read QR codes

How to use it:
1. Run `deft <group>` to list commands, or `deft find "<what you want>"` to search. If it says `no command does this`, use another tool.
2. Run `deft <group> <command> --help` for options and examples.
3. `deft convert <in> -o <out.ext>` converts between formats by extension.
4. Results are one line starting with `ok`, `partial` or `error`; add `--json` to parse them. Errors include a `hint:` with the fix.

Inputs are never overwritten; pass `--force` or `--in-place` to allow it. Globs and directories work as inputs; several inputs run in parallel.

If `deft` is not installed, ask the user, then follow https://github.com/firstprayer/deft/blob/main/docs/INSTALL.md

thumbs/camera.jpg 16.5 KB · 200x150

thumbs/earth.jpg 16.9 KB · 200x200

thumbs/sideways.jpg 15.9 KB · 200x150

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