Elon Musk Fires Warning at Anthropic Over Claude AI Access Block
Elon Musk has issued a sharp public rebuke to AI company Anthropic. This comes after Anthropic blocked his startup xAI from accessing its Claude coding models. The Tesla CEO called the move "not good for their karma" in a recent statement. He simultaneously acknowledged Anthropic's achievements in coding technology.
Anthropic Cuts Off xAI Through Cursor Platform
The conflict emerged when Anthropic restricted xAI's access to Claude through Cursor. Cursor is a popular AI-powered coding platform used by developers worldwide. According to an internal email from xAI cofounder Tony Wu, viewed by tech journalist Kylie Robison, this is a new policy. Anthropic is now enforcing this restriction across all major competitors, not just Musk's company.
Wu wrote to his team on Wednesday about the issue. "I believe many of you have already discovered that Anthropic models are not responding on Cursor," he stated. "According to Cursor, this is a new policy Anthropic is enforcing for all its major competitors."
Terms of Service Violation Triggers the Block
The block stems directly from Anthropic's terms of service. These terms explicitly prohibit customers from using its AI models to build competing products. They also ban using the models to train rival systems. xAI employees had been using Claude through Cursor to accelerate their development work. This usage apparently crossed the line into competitive territory that Anthropic would not tolerate.
Wu acknowledged the productivity impact in his message to the xAI team. However, he framed it as a motivational push. "We will get a hit on productivity, but it really pushes us to develop our own coding product/models," he wrote.
Musk's Mixed Response on Social Media
Musk responded to the situation on his social media platform X. His reaction blended competitive fire with genuine respect for Anthropic's work. He admitted that while the upcoming Grok 4.2 might outperform Claude Opus 4.5 in several areas, coding would not be one of them—at least not immediately.
The timing adds another layer to this dispute. Musk recently promised a "major upgrade to Grok Code" coming next month. He claimed it would "one-shot many complex coding tasks."
Anthropic's History of Blocking Rivals
This is not Anthropic's first move to restrict competitor access. The company previously revoked OpenAI's API access in August. This happened after discovering that ChatGPT maker was using Claude to develop its upcoming GPT-5 model. Anthropic also limited access for coding platform Windsurf last year. This occurred after acquisition rumors involving OpenAI surfaced.
Exploding Demand for Claude Code
These restrictions come as demand for Claude Code has skyrocketed. Anthropic recently announced new rate limits due to unprecedented usage. The company cited cases of users consuming tens of thousands of dollars in model usage on basic subscription plans. Some users were running Claude Code continuously in the background around the clock.
With Claude currently leading multiple coding benchmarks, the stakes are high. It outperforms xAI's Grok models in programming tasks consistently. Anthropic appears determined to protect its technical edge. This stance means burning bridges with one of tech's most prominent figures.
The situation highlights the intense competition in the AI coding space. Companies are fiercely guarding their advantages as the market expands rapidly.
