Benchmark Performance and Token Efficiency

GPT-5.5 leads Terminal Bench (complex CLI workflows) at 82.7% accuracy, outperforming competitors, and Sway Bench Verify (GitHub issue resolution) at 58.6%, trailing Opus-4.7 slightly. Key advantage: 1/4 the tokens of GPT-5.4 and 1/3 of Opus-4.7 per task due to fewer steps, retries, and tokenizer efficiency, making it faster, consistent, and cheaper for end-to-end coding despite 20% higher pricing ($5/1M input tokens, $30/1M output, 50¢/1M cached). Tops AI Index at half the cost of rivals; excels in browser control and agentic tasks.

Strengths in Engineering Workflows with Harnesses

Pairs with tools like Codeex or Kilo CLI (open-source agent with free $25 API credits) for full tasks: refactors, debugging, testing across codebases. Handles long-context reasoning, tool use, assumption-checking. Demos include CS:GO clone (map, shooting cooldowns, minimap, Three.js textures/animations), standalone Minecraft clones (block breaking, water physics, infinite terrain, ores/caves), Mac OS UI clone (SVG icons for Safari, Mail, Maps, apps; brightness/volume controls). Detailed prompts yield better results than vague ones; shines in game dev, front-end.

Front-End, SVG, and 3D Generation Quality

Superior SVG output over Opus-4.7: butterflies, paintings, PS5/Xbox controllers (strong structure despite quirks). Front-end: CRM dashboards via ChatGPT (charts package), landing pages (dynamic typography/movements), Pokemon clone (attack animations). 3D: Off-road SUV physics sim (terrain, rocks, hills). Weaker on 360° product viewers (2D fallback, 4/10 score). Integrates GPT Image 2 for dynamic textures/UI in Codeex. Available to paid ChatGPT users (enable 'thinking-5.5'); API via OpenAI or Kilo.