AI Analysis Tools

Important: Use Scripts First

ALWAYS prefer the scripts in scripts/ over raw curl API calls. Scripts are located in the scripts/ subdirectory of this skill's folder. They provide features that raw commands do not:

• Proper image encoding (WebP conversion, alpha removal)
• Appropriate model selection for each task
• Structured output handling (boolean responses via exit codes)
• Meaningful exit codes for shell integration

When to read the script source: If a script doesn't do exactly what you need, or fails due to missing dependencies, read the script source. The scripts encode Gemini API best practices (image ordering, structured output schemas, model selection) that may not be obvious—use them as reference when building similar functionality.

Quick Start

Environment: Set GEMINI_API_KEY before running any commands.

Dependencies: curl, jq (all tools); base64, magick (image tools only)

# Describe an image (generate alt-text)
scripts/screenshot-describe screenshot.png

# Compare two images for visual differences
scripts/screenshot-compare before.png after.png

# Generate essay-length analysis from text
scripts/emerson "Summarize the key changes" < documentation.md

# Evaluate a boolean condition against text
echo "Hello world" | scripts/satisfies "is a greeting"

Script Overview

screenshot-describe

Generate concise alt-text for an image. Optimized for UI captures.

scripts/screenshot-describe IMAGE [PROMPT]

Exit codes: 0 success, 1 error, 127 missing dependency

screenshot-compare

Compare two images for visual differences. Identifies layout shifts, color changes, padding, and text updates.

scripts/screenshot-compare IMAGE1 IMAGE2 [PROMPT]

Exit codes: 0 differences found, 1 error, 2 images identical, 127 missing dependency

emerson

Generate essay-length (~3000 words) analysis from text input. Produces authoritative, footnoted Markdown.

scripts/emerson "PROMPT" < input.txt

Exit codes: 0 success, 1 error, 127 missing dependency

satisfies

Evaluate whether input text satisfies a condition. Returns boolean via exit code.

echo "text" | scripts/satisfies "CONDITION"

Exit codes: 0 true (satisfies), 1 false (does not satisfy), 127 missing dependency

Examples:

# Check if file mentions a topic
cat file.txt | scripts/satisfies "mentions Elvis" && echo "Found it"

# Validate content type
cat response.json | scripts/satisfies "is valid JSON with an 'id' field"

# Use in conditionals
if cat log.txt | scripts/satisfies "contains error messages"; then
  echo "Errors detected"
fi

Image Encoding Notes

• Images converted to lossless WebP for consistent encoding
• Alpha channel removed (-alpha off) so transparency-only differences are ignored
• Base64: use -w 0 (Linux) or -b 0 (macOS) for single-line output
• Single-image prompts: image before text (Gemini best practice)
• Multi-image comparison: text before images (Gemini best practice)

Safety Notes

• Scripts require network access to the Gemini API
• GEMINI_API_KEY must be set in the environment
• API calls may incur usage costs
• Large images increase request size and latency
• Scripts do not store or log input data

References

• Command Index - Detailed documentation for each script
• Troubleshooting - Common issues and solutions