Anthropic is implementing new restrictive policies concerning the usage of their Claude Code Max subscriptions. Previously, developers could use these subscriptions within third-party tools such as Open Code, Crush, or custom agents. However, Anthropic is now actively blocking such access, issuing error messages stating that credentials are "only authorized for their official CLI." This move is characterized as an "unforced error" and a "walled garden" strategy, aiming for vendor lock-in by forcing developers to use Anthropic's controlled interfaces rather than their preferred tools.

A notable example of this crackdown involves XAI staff, who were reportedly cut off from Anthropic models even though they were using a standard integrated development environment (IDE) like Cursor, not a "hacky wrapper." This suggests that Anthropic is banning competitors from utilizing their technology for code development, creating a hostile environment where a developer's employer or choice of editor can lead to their API key becoming worthless.

The text posits that this action is not primarily driven by concerns over cost or abuse but rather by a desire for control. This is highlighted by Anthropic's contradictory stance: they allow authentication with Claude code subscriptions if an agent is built using their specific Agent SDK, which offers subsidized tokens. However, tools like Open Code or Crush, which perform similar functions but operate outside this SDK or provide a different user interface, face bans. This implies that Anthropic tolerates compute usage only when it keeps users within their proprietary ecosystem.

In stark contrast, other major AI providers, including Google, OpenAI, GLM (GLMEU AI), and Minamax (Minax), are adopting an open integration approach. They are actively supporting the "bring your own harness" philosophy, allowing developers to use their models within third-party environments. For instance, Open Code now officially supports using ChatGPT Plus or Pro plans for its coding agent, providing access to OpenAI's CodeX models without additional per-token API fees. Similarly, Google's Gemini Pro and even Claude 4.5 Opus (via Anti-Gravity) are accessible within Open Code. GLM's DevPac and Minamax's dedicated coding plans also adhere to a philosophy that allows integration with virtually any development environment, simply providing the intelligence layer.

The text critiques Anthropic's selective enforcement of its rules. While banning small tools or perceived rivals, they do not block access for Cursor, despite Cursor developing its own models and thus being a competitor. This apparent double standard is attributed to Anthropic's desire to retain revenue, marketing benefits, and bragging rights associated with being integrated into a popular AI editor like Cursor.

The suggested alternative for developers is to leverage Open Code's capabilities to connect to OpenAI, Google, and other open providers. This process is described as simple, involving commands like /connect or open code O within Open Code's command palette to authorize subscriptions from these providers. This offers developers the freedom to use powerful AI models in their chosen coding environment, bypassing Anthropic's restrictions.