Two AIs are better than one: how OpenAI's plugin lets Claude and Codex debate each other

OpenAI has released an open-source plugin that gives Claude Code structured integration with Codex — OpenAI's own AI agent. Everything works directly from VS Code through the Claude Code Extension, without switching between interfaces. On Habr, a detailed practical analysis of this setup appeared: the author demonstrates from personal experience how to turn two AI advisors into genuinely structured opponents — and why this approach works even beyond tasks directly related to code.

The core problem this approach solves is well known to anyone working with large language models. A single AI has no internal incentive to challenge its own conclusions. It is constrained by training conditions, prone to self-confirmation, and typically does not deviate from its initial position, even when arguments supporting it are weak.

In the classical scenario, it is the user who is forced to take on the role of opponent: asking clarifying questions, requesting consideration of alternatives, independently finding flaws in the proposed logic. This requires time, expertise, and constant critical attention — resources that are always in short supply in the flow of real work. Two AI systems from different vendors solve this problem differently.

Claude was developed by Anthropic's team with emphasis on safety and precise instruction following; Codex was created by OpenAI with a focus on deep understanding and code generation. These models have different strengths, different blind spots, and different principles for evaluating answer quality. When one AI formulates a conclusion and the other challenges it from the position of a fundamentally different training base — this is no longer a theatrical performance, but a collision of two different knowledge spaces.

The result often turns out to be better than if the same query were rephrased multiple times and asked to a single model. Before the plugin appeared, managing dialogue between two AI systems was organizationally inconvenient: two open interfaces, manual context copying between them, constant oversight to ensure both models work with identical data. The new plugin from OpenAI eliminates these frictions: Claude Code gains a direct channel to Codex, and the user remains in the familiar VS Code environment and can leverage both agents in a unified workflow.

The author of the article went further than simple integration and describes additional skills for Claude Code — custom instructions that structure the AI debate. According to him, these skills transform the interaction of two agents from chaotic banter into a managed process with clear roles: one AI formulates and defends a position, the second methodically searches for vulnerabilities in it. Without properly configured skills, the first attempts to launch dialogue between two models yielded little useful — the author acknowledges this honestly.

There are plenty of practical scenarios: code review with cross-checking, generation of competing architectural solutions, intentional search for logical vulnerabilities when one agent deliberately attacks another's proposal. But the author's most interesting observation concerns non-technical tasks: when analyzing business decisions, evaluating architectural compromises, or developing complex arguments, two opposing AI systems consistently deliver richer and more unbiased results than a single model — however strong it might be. A multi-agent approach with different vendors is not merely a doubling of computational resources, but an attempt to embed in the workflow what was previously ensured only by human expertise: an independent second opinion.

Now it is available directly in the IDE — and, unlike a colleague, is never busy and always ready to argue.