Enterprise AI agent platform WRITER released its new flagship model, Palmyra X6, on August 13, 20261. What stands out is how it was built: WRITER states that X6 was post-trained on top of the open-weights GLM 5.21. Pricing is $2 per million input tokens and $8 per million output tokens1.
WRITER says it built new internal evaluations based on production workflows its customers actually run, rather than public benchmarks, and that X6 averaged 0.87 out of 1.00 across nine capabilities including grounding and retrieval, tool use, and sub-agent delegation1. On that internal evaluation, the company says X6 delivered the best combination of capability and cost among the models it tested, including Claude Opus 4.8 and GPT-5.5 — though these are WRITER’s own measurements, not independent verification1. It is an instance of an open-weights model such as the GLM series Z.ai has been releasing serving as the foundation for a US enterprise vendor’s flagship.
Sources
- WRITER Makes Agentic AI Economically Sustainable at Enterprise Scale With Palmyra X6 Release and Major Harness Upgrades - WRITER official press release (August 13, 2026)