GPT OSS 120B vs Claude Fable 5.2
Compare GPT OSS 120B and Claude Fable 5.2 side-by-side. See comparisons of price, response speed, accuracy, and file support to choose the best model for your task.
Overview
GPT OSS 120B vs Claude Fable 5.2 Overview
Everything you need to know about these AI models, including capabilities, performance, pricing, and technical details.
OpenAI / GPT OSS 120B
lightDescription
OpenAI's open-weight reasoning model, and its first open release since GPT-2. GPT OSS 120B is built for agentic work, tool use, and configurable reasoning, activating only a small fraction of its parameters per token, thereby running efficiently. It exposes its full chain of thought, which most closed models hide. Text only, with a moderate context window. Apache 2.0 licensed, so the weights are public and freely deployable. Free to start on Aymo.
Anthropic / Claude Fable 5.2
maxDescription
Anthropic's most capable model and the upgrade to Fable 5.1. Anthropic reports it is a step above Opus 5.5 in almost every area it tested, with large gains in coding and chart reading, and output up to 30% faster than Fable 5.1. It reads text, images, and files across a very large context, supports web search, and offers effort from Low to Max.
About
About
Capabilities
Capabilities
Comparison
Why Use GPT OSS 120B and Claude Fable 5.2?
Aymo gives you more than access to individual models—it provides a complete multi-model AI workspace designed for productivity.
OpenAI / GPT OSS 120B
lightAgentic Coding And Tools
OpenAI built it for agentic workflows with strong instruction following and native tool use, including web search and Python execution. Suited to multi-step development work rather than the hardest frontier engineering.
Reasoning
Configurable reasoning at low, medium, and high effort, with full chain-of-thought exposed rather than hidden. You can follow how it reached an answer, which helps debugging and trust. OpenAI reports it near o4-mini on core reasoning.
A Moderate Context Window
Handles a moderate context window, roughly 96,000 words. Enough for long documents, multi-turn conversations, and substantial codebases, though well short of the million-token frontier models.
Structured Output
Supports structured outputs and a JSON schema, so it slots into applications and agent pipelines rather than only chat. Built for developer workflows that need predictable, parseable responses.
Analysis Through Tools
Reasons for what you supply, and you can browse or run code when tools are connected. It has no built-in knowledge of current events beyond training, so live data comes through the tools you attach.
Text Only Input
Reads and writes text. No image, audio, or video input. Screenshots, diagrams, and scanned pages are outside what it reads, so it works only from text and code.
Anthropic / Claude Fable 5.2
maxTop FrontierCode Score
Anthropic reports 49.1% on FrontierCode 2.0 at Xhigh effort, up from 32.4% for Fable 5.1. That is the highest score of any released model Anthropic tested.
Effort Low To Max
Effort runs Low, Medium, High, Xhigh, and Max, with Medium as the default. At Medium, Anthropic reports it finishes hard tasks with fewer tokens than Fable 5.1.
Room For Whole Projects
A very large context window on Aymo, with room for a full codebase or a long document set. Load everything once and work across it in one session.
Expert Technical Work
Anthropic built Fable for its most ambitious, open-ended technical work. It can also act as an advisor to smaller models or hand simpler tasks to them.
Fewer Needless Refusals
Supports web search on Aymo. Anthropic reports about 55% fewer blocked legitimate requests than Fable 5.1, with similar protection against cyber and biology risks.
Text, Image, And Files
Reads text and images, plus files you upload on Aymo. On Chartography, a chart-reading test without tools, Anthropic reports 73.4%, up from 44.8% for Fable 5.1.
Why Aymo
Why chat with GPT OSS 120B and Claude Fable 5.2 on Aymo AI?
Aymo gives you more than access to GPT OSS 120B and Claude Fable 5.2—it provides a complete multi-model AI workspace designed for productivity.
Compare Responses
See how GPT OSS 120B and Claude Fable 5.2 performs alongside Claude, Gemini, Grok, and other leading AI models.
One Workspace
Keep all your AI conversations, files, and prompts in a single organized workspace.
Switch Models Instantly
Move between different AI models without restarting your conversation.
Upload Once
Use the same files across multiple AI models without uploading them again.
Save & Organize
Bookmark important chats, organize projects, and return anytime.
Work Together
Share conversations and collaborate with teammates in one place.