Anthropic surprised the developer community on Friday by supporting a rival mechanism created by OpenAI to pass marching orders to AI agents. The change makes life simpler for people who use both platforms.
Claude Code engineer Thariq Shihipar announced the update in a social media post. He stated that starting in version 2.1.277, Claude will check for and use AGENTS.md if a CLAUDE.md file is missing from a folder.
Users of Claude Code can toggle this behavior using the /config command, according to Shihipar.
Before this update, developers using Claude Code alongside OpenAI Codex or other non-Anthropic tools had to maintain two separate sets of Markdown instructions. They managed both CLAUDE.md and AGENTS.md, alongside project-specific versions.
Coding agents read these documents with every request. The files outline expected behavior, preferred tool usage, and coding conventions, establishing the foundation of the agent context.
The two formats share similarities but are not identical. CLAUDE.md may contain instructions specific to Claude, while AGENTS.md remains tool agnostic.
Because these documents frequently change, developers working with AI agents previously used workarounds like symlinks to keep CLAUDE.md and AGENTS.md in synchronized states.
OpenAI contributed AGENTS.md to the Agentic AI Foundation under the Linux Foundation last year to build support for its standard. More than 60,000 open source projects implemented AGENTS.md as of December 2025.
The popularity of Claude Code previously allowed Anthropic to push its own standards. However, the company determined that maintaining specification separatism offered no further benefits.
For developers using AI coding tools, this detente represents an event of modest significance. Numerous widely followed software developers praised the decision online.
Thibault Sottiaux, OpenAI head of core product, posted that this is the way and welcomed Anthropic to the light. Shihipar responded with a handshake emoji.
Claude Code version 2.1.277 is available now for developers utilizing the tool.
