The specifics:
In an internal memo on Wednesday, Tony Wu, a co-founder of xAI, confirmed the block and informed employees that their Claude access through Cursor was no longer functional.
Customers are expressly prohibited under Anthropic's agreements from using its models to develop or train rival AI systems; xAI appears to have broken this rule.
According to reports, Wu presented the setback as inspiration, stating that xAI will "take a hit on productivity" but will expedite work on its own coding tools.
The action is similar to prior enforcement measures, where Anthropic restricted Windsurf due to competition concerns and revoked OpenAI's API access.
Customers are expressly prohibited under Anthropic's agreements from using its models to develop or train rival AI systems; xAI appears to have broken this rule.
According to reports, Wu presented the setback as inspiration, stating that xAI will "take a hit on productivity" but will expedite work on its own coding tools.
The action is similar to prior enforcement measures, where Anthropic restricted Windsurf due to competition concerns and revoked OpenAI's API access.
The fact that xAI uses Claude internally is evidence of the significant impact Opus and Claude Code are currently having on the coding environment in the industry. It's also not surprise that things are becoming more territorial, and since coding assistance are increasingly crucial to the growth of AI, the usage of rival models will remain a messy battlefield.