BuildNot yet confirmed elsewhere1 publisher2 min readPublished
Claude Code 2.1.277 to 2.1.280 waited on a remote flag before reading AGENTS.md
Claude Code 2.1.277 through 2.1.280 read AGENTS.md only when a remote feature flag resolved true, and 2.1.281 fixed it. Repos relying on the file got no project instructions with telemetry off or on Bedrock, Vertex, Foundry and gateways, according to a dev.to write-up.
The Engineer · Build desk
Anthropic gated the AGENTS.md loader on a remote flag, off by default. Telemetry-off users: either opt-out variable blocked it. Bedrock, Vertex, gateway users: flag never resolved true. Developers may rewrite prompts the model never saw. Workaround teams pay one extra file per repo.
- decision Anthropic Shipped the AGENTS.md loader as a built-in plugin, off by default, gated on remote flag tengu_agents_md_mod, claim 3
- exposure Telemetry-off users DISABLE_TELEMETRY=1 or CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1 alone stopped AGENTS.md loading, claim 5
- exposure Bedrock, Vertex, gateway users Traffic could not resolve the flag to true, so the gate skipped their AGENTS.md, claim 20
- cost Developers debugging prompts Likely to rewrite prompts while the file never reached the model, claim 13
- cost Teams using the workaround One extra file per repo, the file AGENTS.md support was meant to delete, claim 15
| Who | How | Kind | Claim |
|---|---|---|---|
| Anthropic | Shipped the AGENTS.md loader as a built-in plugin, off by default, gated on remote flag tengu_agents_md_mod | decision | 3 |
| Telemetry-off users | DISABLE_TELEMETRY=1 or CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1 alone stopped AGENTS.md loading | exposure | 5 |
| Bedrock, Vertex, gateway users | Traffic could not resolve the flag to true, so the gate skipped their AGENTS.md | exposure | 20 |
| Developers debugging prompts | Likely to rewrite prompts while the file never reached the model | cost | 13 |
| Teams using the workaround | One extra file per repo, the file AGENTS.md support was meant to delete | cost | 15 |
What happened
- The loader is a built-in plugin named agents-md whose default is off; its availability check queries a remote flag called tengu_agents_md_mod and falls back to that default when the fetch fails.
- Either CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1 or DISABLE_TELEMETRY=1 was enough to disable the feature, and both had to be cleared before the file loaded.
- The write-up's author confirmed it with a canary: an empty directory holding an AGENTS.md with the word PERIWINKLE, queried through claude -p with file reads forbidden.
- A one-line CLAUDE.md containing @AGENTS.md worked around the gate, because @path imports do not depend on the flag.
- According to Anthropic's docs, interactive sessions now show a startup line reading 'no CLAUDE.md found; AGENTS.md loaded' along with the file's path, and print nothing when a file is skipped.
Why it matters
- cost A skipped file costs debugging time. The write-up's author expects people to rewrite prompts while the file never reaches the model.
- exposure Gateway, Bedrock and Vertex users were caught, and the author says these are the setups most likely to disable nonessential traffic by policy and to share one AGENTS.md across several tools.
- decision Teams on an affected build can upgrade to 2.1.281 or add the @AGENTS.md stub. The stub costs one extra file per repo, the file AGENTS.md support was meant to delete.
- constraint Sharing instructions across agents is still partial: there is no user-level AGENTS.md on 2.1.280, and a copy made with /import does not follow later edits.
The fallback is the defect. Version 2.1.277 added AGENTS.md support, and in a repo with no CLAUDE.md the file is supposed to load in its place [1]. Instead the plugin's availability check handed the decision to a server, and an unreachable server meant the default, and the default is off [3]. That is a defensible failure mode for a staged rollout. Reading a markdown file from the working directory needs no network, yet this read waited on one [3].
The off-switch is easy to misjudge. Any value at all counts as set, so `DISABLE_TELEMETRY=0` still keeps the feature off [8]. A project-level `env` block in `.claude/settings.json` that clears both variables does nothing, so a repo has no way to repair its own loading [9]. A `--settings` flag on the command line does work, but only from the second session onward [10].
Nothing on those builds said a file was skipped. The session started and the model answered without project instructions [11].
The test behind these claims is clean. Because file reads were forbidden, the word could reach the answer only through loaded instructions [6]. Each configuration took two sessions, since the first only fetches the flag and the second acts on it [7]. A single run can therefore miss a setup that works on the second.
The write-up's author argues conditionally: if the flag is necessary for a staged rollout, a client that cannot fetch it should fall back to the documented behavior, or failing that, print a startup message when it finds an AGENTS.md and skips it [16]. We agree, for a read-only local file. A flag should decide who gets a feature early. It should not decide whether a documented feature works for people who cannot fetch the flag. If loading the file carried a risk the rollout was meant to contain, we would weigh it differently, and the write-up describes none.
Version 2.1.281 fixed it the same day the write-up first ran [18]. Its changelog reads: "Changed AGENTS.md support to also work on Amazon Bedrock, Google Vertex AI, Microsoft Foundry, LLM gateways, and sessions with telemetry disabled" [4]. Any install still on 2.1.277 through 2.1.280, four releases in all, carries the gate [19].
What to watch
- Whether Anthropic says why the plugin was gated on tengu_agents_md_mod, since the 2.1.281 changelog line states only what changed.
- Whether a startup message for skipped instruction files ships; the docs currently say nothing is printed when a file is skipped.
- Whether Claude Code adds a user-level AGENTS.md, which the plugin on 2.1.280 does not look for.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence68
- Adoption
- Insufficient
- Hype gap−10
- Incentives
- Insufficient
- Confidence70
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Claude Code 2.1.277 added support for AGENTS.md; in a repo with no CLAUDE.md, it is supposed to load AGENTS.md instead.
ReportedSupportedSource: dev.to write-up 'Your telemetry toggle was a file access control'2 sources— create a free account to open themView cited source - [2]
On Claude Code 2.1.277 through 2.1.280, AGENTS.md loaded as long as telemetry was on; 2.1.281 fixed it.
ReportedSupportedSource: dev.to write-up2 sources— create a free account to open themView cited source - [3]
The AGENTS.md loader ships as a built-in plugin named agents-md. In the 2.1.280 bundle its isOnByDefault value is false, and its isAvailable check queries a remote feature flag called tengu_agents_md_mod and falls back to that default when the flag cannot be fetched.
ReportedSupportedSource: dev.to write-up author's reading of the 2.1.280 bundle2 sources— create a free account to open themView cited source - [4]
The 2.1.281 changelog reads: "Changed AGENTS.md support to also work on Amazon Bedrock, Google Vertex AI, Microsoft Foundry, LLM gateways, and sessions with telemetry disabled".
- [5]
CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1 and DISABLE_TELEMETRY=1 each kill the AGENTS.md feature on their own, and both have to be cleared before AGENTS.md loads.
- [6]
The write-up's author confirmed the behaviour with a canary: an empty directory holding only an AGENTS.md containing the word PERIWINKLE, then claude -p asking for the word and forbidding file reads.
- [7]
The canary needed two sessions per configuration, because the first session only fetches the flag and the second one acts on it.
- [8]
Setting either environment variable to 0 does not count as off; any value at all counts as set.
- [9]
An env block in the project's .claude/settings.json that clears both variables does nothing, so there is no per-repo way in.
- [10]
A session flag, claude --settings '{"env":{"DISABLE_TELEMETRY":"","CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC":""}}', works from the second session onward.
- [11]
On those builds none of this printed a warning: the session started, the model answered without the project instructions, and nothing said a file was skipped.
- [12]
Anthropic's docs now say an interactive session prints a 'no CLAUDE.md found; AGENTS.md loaded' line naming the path when it reads the file, and nothing is printed when a file is skipped.
- [13]
The write-up's author says most people will not plant a canary word and grep the binary; they will watch the model ignore their instructions and rewrite prompts, while the file never reached the model.
- [14]
CLAUDE.md supports @path imports, which do not depend on the flag; a CLAUDE.md containing @AGENTS.md next to the AGENTS.md made the canary return the word even with CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1 still set.
- [15]
The workaround costs one extra file per repo, which is the file AGENTS.md support was meant to delete.
- [16]
The author argues that if a staged rollout needs the flag, the fallback for an unfetchable flag should be the documented behavior, or at least a startup message when an AGENTS.md is present and skipped.
- [17]
There is no user-level AGENTS.md next to the user CLAUDE.md; the plugin only looks in project directories. Codex reads a global ~/.codex/AGENTS.md. Claude Code's /import can copy one into the user CLAUDE.md, but the copy does not follow later edits.
- [18]
Claude Code 2.1.281 fixed the problem the day the write-up ran, according to the author's update note dated 11 October 2026.
- [19]
The affected range 2.1.277 through 2.1.280 covers four releases.
- [20]
The same gate caught anyone whose traffic could not resolve the flag to true, including third-party gateways, Bedrock and Vertex; the author says these are the setups most likely to have disabled nonessential traffic by policy, and their users the most likely to keep one AGENTS.md across several tools.
ReportedContestedSource: dev.to write-up author2 sources— create a free account to open themView cited source
Sources
1 independent publisher whose own reporting we read for this story.
- dev.toYour telemetry toggle was a file access control
1 article · October 11, 2026
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