We checked 3,905 CLAUDE.md and AGENTS.md files on GitHub. In 1 in 6 repos, Claude never reads the AGENTS.md
On October 18, 2026 we pulled 3,905 CLAUDE.md and AGENTS.md files from public GitHub repositories and ran each one through the same checks. We wanted to know something simple: does the file actually reach the agent? Four results stand out. In about 1 in 6 repos that keep both files at the root (16%), the CLAUDE.md never mentions the AGENTS.md, so Claude Code never loads it. In another 15%, a…
Between October 18 and October 19, 2026, researchers analyzed 3,905 CLAUDE.md and AGENTS.md files from public GitHub repositories, checking if Claude Code read AGENTS.md by default. Four key findings emerged from the study.
In roughly one-sixth of repositories containing both files at the root, CLAUDE.md never mentioned or referenced AGENTS.md, meaning Claude Code would not load it. In an additional 15% of cases, a sentence within CLAUDE.md requested Claude to read AGENTS.md, but success depended on Claude deciding to open the file. In 7% of situations, the CLAUDE.md and AGENTS.md files had diverged over time, causing Claude and Codex to follow separate rules within the same repository.
Nineteen percent of CLAUDE.md files exceeded the recommended 200 lines, with the median length being 81 lines. Meanwhile, 2.6% of AGENTS.md files surpassed GitHub's default 32 KiB size limit, with 51,840 exceeding the 24 KiB threshold. Despite these size variances, CLAUDE.md typically contained around 81 lines, with 19% surpassing the 200-line recommendation set by Anthropic.
The study also examined the prevalence of various file relationships. In 36% of instances where an AGENTS.md file resided at the repository root, a CLAUDE.md file was present alongside it. The outcomes of CLAUDE.md were as follows:
- 25% of CLAUDE.md files imported AGENTS.md using "@AGENTS.md",
- 23% of CLAUDE.md files served as symlinks to AGENTS.md,
- 7% of CLAUDE.md files copied AGENTS.md contents verbatim,
- 7% of CLAUDE.md files held AGENTS.md contents as a second copy,
- 7% of CLAUDE.md files partially mentioned AGENTS.md, relying on Claude's decision to open the file,
- 15% of CLAUDE.md files only mentioned AGENTS.md if Claude opened it, and
- 16% of CLAUDE.md files made no reference to AGENTS.md at all.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
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