Borrowing it
Nothing to install: this file belongs to braintrustdata/bt. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/braintrustdata/bt/main/AGENTS.mdgit clone --depth 1 https://github.com/braintrustdata/btWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/braintrustdata/bt/agents-md)<a href="https://agentmods.dev/instructions/braintrustdata/bt/agents-md"><img src="https://agentmods.dev/badge/instructions/braintrustdata/bt/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/braintrustdata/bt/agents-md"><img src="https://agentmods.dev/badge/instructions/braintrustdata/bt/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00964 | $0.00964 |
| Opus 5.5 | $0.00386 | $0.00386 |
| Sonnet 5.5 | $0.00193 | $0.00193 |
| Haiku 4.5 | $0.00096 | $0.00096 |
Grade A, and why
bt AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent Guidelines
Configuration Policy
- Do not introduce new ad-hoc configuration reads via
std::env::var(...)/process.env/os.getenv(...)in command logic. - All user-facing/runtime configuration must be defined in
claparguments:- a CLI flag, and
- for persistent configuration, a corresponding environment variable (
#[arg(env = ...)]).
- User-facing environment variables must use the
BRAINTRUST_prefix (for exampleBRAINTRUST_EVAL_WATCH), matching the Braintrust SDKs. Do not add newBT_*names;DEPRECATED_BT_ENV_VARSinsrc/env.rsonly keeps old names working.BT_EVAL_*/BT_DATASET_PIPELINE_*remain the internal protocol for runner subprocesses. - Entry points/runners should receive configuration from the CLI layer (via args/env that the CLI owns), not from independent, undocumented env lookups.
- Extreme edge-case exceptions are allowed only when a flag is not feasible (for example, process-internal plumbing), and must be:
- documented inline with a short rationale, and
- minimized in scope.
- Do not infer/transform app URLs from API URLs (for example, replacing
api.withwww.). Treat--app-url/BRAINTRUST_APP_URLas the source of truth for app URLs.
BTQL Safety
- BTQL queries over
project_logs(...)or the combinedproject(...)source must include a useful segment-elimination constraint:- a selective range on
created,_xact_id, or_pagination_key; or - scoping to specific
root_span_idoridvalues.
- a selective range on
- This requirement does not apply to other object sources such as
project_functions(...),project_prompts(...),dataset(...), orexperiment(...).
Tooling
- This repo is managed with
miseandpre-commit; prefer using the repo-defined toolchain and hooks when running local validation.
Privacy and Test Data
- Do not add real customer, organization, profile, project, function, dataset, experiment, or user names/IDs to tests, fixtures, docs, examples, snapshots, or committed files.
- Use synthetic placeholders instead, for example
test-profile,test-org,test-project,fn_test_topic_map, or UUIDs clearly marked as fake. - If a user-provided command includes real identifiers, do not copy them into code or tests; translate them to synthetic values before writing files.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday Changed · +2 lines · +266 tokens per session eb4524d7f3b0
- 16d ago Changed · +1 lines · +91 tokens per session fdd996ac440f
- 2mo ago First seen · 40 lines · 607 tokens per session scan A 12bcb8b44604
bt AGENTS.md is an instructions file published in the GitHub repository braintrustdata/bt (14 stars, last pushed today), licensed Apache-2.0. It adds 964 tokens to every session, about $0.0039 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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