While the market for AI continues to expand, the latest move by Anthropic has raised eyebrows in the industry. With the number of companies eyeing the top spot, the company behind the Claude models is rumoured to be restricting access of Anthropic models for developers at xAI, the artificial intelligence firm founded by Elon Musk. The decision reportedly followed internal concerns that Anthropic’s technology was being used through third-party tools like Cursor to accelerate work at a direct competitor. According to internal emails, the block could slow development but may also push xAI to double down on its own models.
On Wednesday, xAI’s cofounder Tony Wu wrote an email to his team where he stated, “Hi team, I believe many of you have already discovered that Anthropic models are not responding on Cursor.” Aside from that, Cursor has also clarified that this is a new policy Anthropic is enforcing for all its major competitors.
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The block happened after xAI employees were using Claude through Cursor to speed up their work. Cursor allows developers to write and improve code with help from different AI models. While Cursor itself is widely used and legal, Anthropic appears to have objected to how its models were being used by a direct competitor. In his email, Wu admitted that losing access would slow the team down. However, he also said it should encourage xAI to focus more on building its own tools and models.
Anthropic’s terms clearly state that its services cannot be used to create competing products or to help train rival AI systems. Even if access comes through another platform like Cursor, the responsibility still falls on the customer. In this case, Anthropic seems to have decided that xAI crossed that line.
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This is not the first time Anthropic has taken such action, as last year, it cut off access to OpenAI under similar conditions. More recently, it restricted access for another coding platform after reports suggested the company might be sold to OpenAI. These steps show a pattern of strict enforcement when Anthropic believes its technology could help competitors.
At the same time as the xAI block, Anthropic has been tightening controls on how third-party tools connect to its systems. Some tools were reportedly trying to access Claude models using cheaper consumer plans instead of standard paid access. An Anthropic employee confirmed that safeguards were strengthened after several accounts were banned for misuse.
The timing of the move is also important. Elon Musk recently said that a major update to Grok Code, xAI’s own coding assistant, is coming soon. He claimed it would be able to handle many complex tasks in a single attempt. Following the Anthropic decision, Nikita Bier, who leads product at X, joked publicly that it might be time to block Anthropic from the social platform.