💪 Anthropic closed Fable 5 and Mythos 5 to foreign users. I found a replacement - and honestly, my stack only won from it
What GLM-5.2 is:
An open model from Z.ai (formerly Zhipu AI) with ~750B parameters, MoE architecture and a 1M-token context window. Released June 16 under the MIT license with open weights on HuggingFace - no regional restrictions and no risk of it getting "switched off" by a regulator's decision. Leader among open-weights models on the Artificial Analysis Intelligence Index, 2nd place on the Code Arena WebDev leaderboard (after Fable 5). Kilo Code benchmark on a planning task: Fable 9.1 vs GLM 9.0 - at 10x lower cost
So I'm not just talking - I looked at the alphaXiv case: a service for automatically reproducing scientific experiments. It also lost Fable and switched to GLM-5.2. In the demo, the agent independently worked on an RL experiment from a fresh paper on two servers with 8xH100 each, within the SkyRL framework
What the GLM-5.2 agent did without an operator:
💡 Fixed the environment on its own - spotted a dependency conflict, picked a strategy and applied the fix without any hints
💡 Compared two RL training modes - fully asynchronous and collocated-synchronous, on competitive programming tasks
💡 Put together the final report - autonomously analyzed throughput and reward stability for both setups
There's one honest limitation: no vision. Where Fable reads a chart as an image - GLM has to parse the numbers through numpy code. For most of my tasks it's not critical, but I'm not going to keep quiet about it
My stack right now - three models, three jobs:
⚡️ Claude Opus 4.8 - complex reasoning, architecture decisions, long context chains
⚡️ Codex 5.5 - autonomous coding, tasks I launch and let go
⚡️ GLM-5.2 - agent pipelines and tasks that need a model that doesn't depend on the mood of American regulators
It's exactly this combo that took my development to another level. Three providers, different strengths, and - most importantly - if one stops being available, the system doesn't go down
⭐️ Simon Willison, AI tools developer (simonwillison.net):
"GLM-5.2 is probably the most powerful text-only open-weights LLM out there today"
🎯 For six months I thought one top closed provider was enough and there was no need to complicate the stack. Turns out, no. An open model with an MIT license isn't a backup option. It's insurance against decisions made without you
🔥 Plug in GLM with my referral - link