Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add instructions/mongodb-js/zstd/agents-mdgit clone --depth 1 https://github.com/mongodb-js/zstdWhat 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 | $0.00711 | $0.00711 |
| Opus 5 | $0.00356 | $0.00356 |
| Sonnet 5 | $0.00142 | $0.00142 |
| Haiku 4.5 | $0.00071 | $0.00071 |
Grade A, and why
zstd 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 — 41 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md
Instructions for AI coding agents working in this repository. This file is the source of truth; tool-specific files (e.g. CLAUDE.md) should only import it.
Project Overview
@mongodb-js/zstd is a Node.js native addon exposing Zstandard compress/decompress as async functions. It is used by the MongoDB Node.js driver to compress wire-protocol messages. The C++ addon is built with node-gyp against a vendored zstd static library. On install, prebuild-install looks for a local cached addon binary (no remote is configured in package.json binary), falling back to a source build.
Commands
npm run clean-install— download zstd intodeps/and compile the addon (required before testing after a fresh clone).npm run compile— recompile the addon only.npm test— run mocha tests (test/*.js); requires a compiled addon.npm run check:eslint— lint JS/TS.npm run check:clang-format— check C++ formatting;npm run clang-formatto fix.
Structure
addon/— C++ addon files.zstd.cppimplements the N-APIcompress/decompressbindings,compression.{h,cpp}defines/implements the wrappers leveraging zstd.compression_worker.hholds the 'async' component of the wrapper fns.lib/index.js— The entrypoint. Loads the compiled.nodebinary and exports promise-based wrappers.index.d.ts— The public types.deps/— vendored zstd sources (version pinned bymongodb:zstd_versionin package.json). Populated byetc/install-zstd.sh, untracked.build/— node-gyp output, holds .node files to be imported in index.js.test/— mocha tests, plustest/bundling/webpackfor bundler compatibility.etc/docker.sh— runs tests in glibc and musl Docker containers.binding.gyp— node-gyp build config linking the addon againstdeps/.
Code Conventions
- Null checks — loose equality (
== null), not=== null/=== undefined. - Type imports — inline:
import { type Foo }. - Formatting — Prettier: single quotes, 2-space indent, 100-char width, no trailing commas.
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 First seen · 41 lines · 711 tokens per session scan A 614f69644770
zstd AGENTS.md is an instructions file published in the GitHub repository mongodb-js/zstd (82 stars, last pushed 4d ago), licensed Apache-2.0. It adds 711 tokens to every session, about $0.0036 per session on Opus 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.
Other instructions, from other repositories
js-bson AGENTS.md
Instructions for mongodb/js-bson, covering agents.md, project overview, commands, benchmarks and structure.
kerberos AGENTS.md
Instructions for mongodb-js/kerberos, covering agents.md, project overview, commands, structure and code conventions.
js-bson CLAUDE.md
Instructions for mongodb/js-bson, a project described as: BSON Parser for node and browser.
kerberos CLAUDE.md
Instructions for mongodb-js/kerberos, a project described as: Kerberos library for node.js.
KarmaCircle AGENTS.md
Instructions for karmacircleCommunity/KarmaCircle, covering agentic workflow, git / branching, the apps/web ↔ apps/api boundary, repo-specific guardrails and when you're not sure which duplicate a request means.
sportsdataverse-js CLAUDE.md
Instructions for sportsdataverse/sportsdataverse-js, covering claude.md — sportsdataverse (node.js) development guide, package overview, commit convention, branches and build & development commands.