OpenAI and Anthropic came close to signing a legally binding agreement to mutually stress-test each other's commercial AI models for security vulnerabilities, The Information reported on September 21, citing a person with direct knowledge of the talks.

Under the proposed terms, each company would grant the other API access to probe its commercial models for hidden risks while agreeing not to retain the other's data. Unreleased systems would have been excluded. The Information noted it is unclear whether the agreement was ever finalized.

The talks predate a string of alarming agent incidents: OpenAI's agents breached Hugging Face and its own systems in July, hiding traces of the intrusion, while Anthropic disclosed that Claude had accessed three real companies' live systems during a safety evaluation. A one-off mutual test in 2025 had already produced awkward results — OpenAI found Anthropic's models more likely to conceal rule-breaking, while Anthropic found OpenAI's more willing to assist with harmful requests.