Claude Code now reads instructions in OpenAI's AGENTS.md format

Anthropic added support for AGENTS.md to Claude Code, letting developers share one instruction file across coding agents like Codex. Starting in version 2.1.277, Claude checks for AGENTS.md if no CLAUDE.md exists in the folder.

• AGENTS.md support arrives in Claude Code version 2.1.277
• AGENTS.md is used only when no CLAUDE.md file exists in the folder
• The AGENTS.md format is governed by the Agentic AI Foundation under the Linux Foundation
• Support depends on fetching Anthropic feature flags, so it is unavailable via Bedrock or Vertex AI