Anthropic announced on Friday that Claude Code will now support OpenAI's AGENTS.md format, a significant step toward interoperability between rival AI coding platforms. Starting with version 2.1.277, if a folder lacks a CLAUDE.md file, Claude Code will automatically check for and use AGENTS.md instead, with users able to toggle this behaviour via the /config command. This decision relieves developers who previously had to maintain separate instruction files for different AI tools.

Developers working with multiple AI platforms previously required two sets of markdown instructions—CLAUDE.md for Claude-specific configurations and AGENTS.md, the tool-agnostic standard OpenAI contributed to the Linux Foundation's Agentic AI Foundation last year. As of December 2025, more than 60,000 open source projects have implemented AGENTS.md. Both companies' leaders publicly celebrated the move, with OpenAI's head of core product commenting "This is the way," and the decision representing a shift away from what the article describes as "specification separatism."