Standard
A markdown file that Anthropic's Claude Code reads automatically to load project-specific instructions, rules, and context for its coding agent.
Files seeded by Claude Code's /init scored a median 8.4 against 7.7 for other CLAUDE.md files in Reporails' scan of 8,220 files. Only about a fifth of an /init file is instruction, against close to three in ten elsewhere.
Reality
Claude Code 2.1.285's Read deny rules let 4 of 11 file-reading routes reach the model in a developer's test, among them grep -r and CLAUDE.md @imports. The docs limit the rules to named paths and point anyone needing a hard block to the OS sandbox.
Reality
Relipa's AI development workflow wraps a coding agent in six stages and fixes the tests before any code is written. Most of its published detail covers the workspace plumbing that runs before a model is ever called.
Reality
Rulestack found a skill file that named a deleted pnpm script for 24 days while 28 commit-time shape tests passed. A 26-line check against package.json exits 1 on any missing name, so a hook can block the commit that deletes a referenced script.
Reality
Huntress ran seven Rails tasks past Claude Fable 5.1 and watched it copy hand-rolled code out of its own repository. Changing the harness, in three cheap steps, took API recall from 48 percent to 100.
Reality
Claude Code started reading AGENTS.md on September 18, but only where no CLAUDE.md sits in the working directory or any parent above it. Monorepos need a stub file per package or a change to the instructionFiles setting.
Reality
A codeword test on Claude Code v2.1.273 put six same-sized memory files in six places. Three arrived at launch, two waited for a Read below them, and one needed an environment variable to arrive at all.
Reality
Version 2.1.277 reads a shared AGENTS.md when no CLAUDE.md is in scope. The documented exceptions cover first sessions, telemetry-disabled runs, Bedrock, Vertex and Foundry, and the hooks governance tooling watches.
Reality
A dev.to template for CLAUDE.md and AGENTS.md swaps style adjectives for Avoid/Preferred code pairs that name the exact helper an agent should call, on the argument that a code shape is the only part a model can imitate.
Reality
A 29-session test on Claude Code v2.1.273 ran the same protected-directory rule two ways, as prose in CLAUDE.md and as a PreToolUse hook. Both held on a plain task. The comparison that separates them rests on four runs.
Reality
Anthropic shipped the AGENTS.md fallback in Claude Code 2.1.277 as a flag-gated built-in mod. Two machines on the same pinned version can load different project instructions. The same week's digest also logs a reverted deny-rule fix.
Perspective Coverage
4 publishersReality
Claude Code's configuration-debugging page says nested memory files load on demand through the Read tool, so a report that the agent ignored the rules starts with /context and the question of whether the file was in the window at all.
Reality
Anthropic's memory documentation sets a 200-line target per instruction file and reserves real blocking for a hook. Everything written in markdown arrives as context the model weighs against your last message.
Reality
shinpr has taken claude-code-workflows through 133 releases, and the recent ones delete structure the models no longer need. His session reader then found three mandatory steps in his own repository that never ran.
Reality
Claude can now read AGENTS.md, the file other agent tools already look for. XDA-Developers reports developers called the change small and long overdue, and the Claude-specific syntax that forced a second file has not moved.
Reality
Claude Code now supports AGENTS.md through a built-in plugin with four loading modes. The default treats the two filenames as alternatives, and the mode itself is set in user or managed settings outside the repo.
Reality
Claude Code now writes its own record of a developer's corrections and preferences. Anthropic's documentation keeps CLAUDE.md alongside it, and the one practitioner account available says the file's remaining job is narrower.
Reality
An XDA Developers writer says his Claude allowance stretched four times further once he stopped letting the agent orient itself inside a 500-file repository. The post does not include token counts, so read it as one practitioner's log.
Reality
Newer models ship with advice to keep the guidance file under 200 lines. The analyst who wrote those 1,042 lines argues each one logs context the model lacked, and that the real debt is a mechanical rule left sitting in prose.
Reality
Go stops at exported and package-wide, so a helper meant for one file can be called from every file in the package. mpyw's linter checks that boundary and reports the crossing at both the declaration and the call.
Reality