As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/v/yt-alex-finn-claude-sonnet-5-just-dropped-i-m-changin/

# Claude Sonnet 5 just dropped. I'm changing how I use AI...

Alex Finn, 31 July 2026, YouTube. 56,688 views as of 9 October 2026.
Kind: Community.
Watch: https://www.youtube.com/watch?v=uU0RFxGv-Ks

## Why it is here

Found 2026-09-29 by YouTube search "introducing claude sonnet 5" (sorted by upload date). Listed as: 56,611 views, length 11:56, published "2mo ago" (so the date above is approximate).

## Description (written by Gemini from the video)

**Summary**  
Alex Finn reviews Anthropic's newly released Claude Sonnet 5, evaluating its benchmark performance, pricing, and agentic coding capabilities. He compares its 3D graphics generation against ChatGPT 5.5, outlines a cost-saving hybrid workflow pairing Claude Opus 4.8 for planning with Sonnet 5 for execution, and examines leaked strings indicating an impending return of Claude Fable 5.

**What is shown**  
- **Benchmark & Cost Breakdown [00:41, 01:29, 03:14]:** Slides comparing Claude Sonnet 5 against Sonnet 4.6 and Opus 4.8 across SWE-bench Verified, Terminal-Bench 2.1, Humanity's Last Exam, OSWorld, and BrowseComp. Alex also shows his personal Hermes API billing dashboard displaying $1,375.94 in Claude usage over the previous month [01:58].
- **Head-to-Head 3D Simulation Test [04:16]:** A prompt requesting a single-file Three.js stormy sea simulation with a wooden sailing ship, Gerstner waves, dynamic lighting, rain, and UI controls is submitted to both Claude Code Desktop (running Sonnet 5) and OpenAI Codex (running ChatGPT 5.5).
- **Output Inspection [04:52]:** The ChatGPT 5.5 generation renders rain particles and controls, but features static ocean meshes and a stationary boat without camera rotation. In contrast, Sonnet 5's generation [05:27] produces an interactive 3D scene with dynamic wave physics, a rolling and pitching ship, and responsive controls.
- **Hybrid Planning Workflow Demo [06:42]:** In Claude Code Desktop, Alex sets Plan Mode to Opus 4.8 in "Ultra Code" mode to design an AI-powered Notion clone, launching five sub-agents in a background workflow [08:31]. Once the architectural markdown plan is generated [08:52], he switches the model to Sonnet 5 (Medium) to execute the implementation cheaply [09:08].
- **Hermes Agent Setup & Fable 5 Leak [09:30, 10:15]:** Switching the model selector in Hermes Agent/OpenClaw to Sonnet 5 via API, followed by a review of leaked Claude Code strings indicating upcoming API billing and identity verification requirements for Claude Fable 5.

**Claims & numbers**  
- **Benchmarks (Sonnet 5 vs Sonnet 4.6 vs Opus 4.8):**
  - **SWE-bench Verified (Agentic coding):** Sonnet 5 scores 63.2% vs Sonnet 4.6 at 58.1% and Opus 4.8 at 69.2% [02:45].
  - **Terminal-Bench 2.1 (Agentic coding):** Sonnet 5 scores 80.4% vs Sonnet 4.6 at 67.0% and Opus 4.8 at 82.7% [02:45].
  - **Humanity's Last Exam (Multidisciplinary reasoning):** Sonnet 5 scores 43.2% with vision / 57.4% text-only vs Sonnet 4.6 at 34.6% / 46.8% and Opus 4.8 at 49.8% / 57.9% [02:45].
  - **OSWorld verified (Computer use):** Sonnet 5 scores 81.2% vs Sonnet 4.6 at 78.5% and Opus 4.8 at 83.4% [02:45].
  - **GPQA Diamond (Knowledge work):** Sonnet 5 scores 1418 vs Sonnet 4.6 at 1395 and Opus 4.8 at 1615 [02:45].
- **Cost vs. Performance:** On the BrowseComp benchmark, Sonnet 5 achieves roughly half the cost per task (~$4.50 vs ~$8.00 on medium effort) compared to Opus 4.8 with only about a 5% difference in pass rate [03:19].
- **Fable 5 Status:** Leaked code strings in Claude Code indicate Fable 5 will require separate credit billing/API usage and US identity verification upon return [10:24].

**Notable quotes**  
- "It is by far the best bang for your buck in AI right now. It has almost the performance of Opus 4.8, but for a fraction of the price." [00:04]
- "When you're doing actual execution, you don't need a ton of compute if the plan mode was done with a lot of compute." [07:44]
- "It is not replacing Opus 4.8 for me. It's only replacing Opus 4.8 for cheap and quick and easy tasks." [11:08]

**Assessment**  
A community review and hands-on workflow tutorial demonstrating practical use cases for Claude Sonnet 5. The Three.js benchmark and Claude Code workflows are shown live in real time on desktop interfaces without misleading edits.

_Described by gemini-3.8-flash on 2026-09-29 from the video's audio and frames._

## How AI was used to make it

AI made a small part of this video (Subject built by AI).
- Interactive Three.js ocean simulations generated by Claude Sonnet 5 and ChatGPT 5.5 demonstrated on screen
Tools: Claude Sonnet 5, ChatGPT 5.5, Claude Opus 4.8
(Classified by gemini-3.8-flash from our description; high confidence. Overview: https://postcutoff.com/ai-video/)

## Related

- 2026-06-30: [Anthropic releases Claude Sonnet 5, "the most agentic Sonnet yet"](https://postcutoff.com/e/2026-06-30-claude-sonnet-5/)

## More videos on this

- 2026-07-31: [I’m freaking out about Sonnet 5](https://postcutoff.com/v/yt-mo-bitar-i-m-freaking-out-about-sonnet-5/), Mo Bitar, YouTube, community, 133,230 views as of 9 October 2026.
- 2026-03-03: [Claude Sonnet 5: Greatest AI Coding Model Ever! 1M Context, Cheap, & More! (Early Test)](https://postcutoff.com/v/yt-worldofai-claude-sonnet-5-greatest-ai-coding-model/), WorldofAI, YouTube, review, 73,113 views as of 8 October 2026.
- 2026-07-31: [NEW Claude Sonnet 5 vs Opus 4.8! (Full Review)](https://postcutoff.com/v/yt-ai-foundations-new-claude-sonnet-5-vs-opus-4-8-full-rev/), AI Foundations, YouTube, review, 48,839 views as of 8 October 2026.
- 2026-07-31: [Claude Sonnet 5 Is HERE – Hands-On With Anthropic’s NEW Model!](https://postcutoff.com/v/yt-bijan-bowen-claude-sonnet-5-is-here-hands-on-with-an/), Bijan Bowen, YouTube, community, 39,375 views as of 7 October 2026.

What else happened that month, day by day: https://postcutoff.com/timeline/2026/06/